user113: Nirvana is considered by many religions the pinnacle to strive for.  What do I need to do to achieve Nirvana?  Are there different perceptions of the requirements held by different sects? 

user-1: I believe that all Buddhist "sects" would say that there is a path to nirvana. In deed this is the "fourth noble truth", though different "sects" interpret it differently, or at least claim that other "sects" have a different understanding of it. For your purposes, maybe that's what the long history of doctrinal debate is actually about.
I believe that all Buddhists claim that meditation is a prerequisite to nirvana, though that seems to take different forms, with different "sects" vying over e.g. the terms "sudden" and "gradual", and with different instructions and communities.
I've put 'sect' in quotes because I'm going to side with what I understand from soto zen, which I think stresses that we "don’t practice zazen in order to get enlightened, we practice being enlightened as we practice zazen". So the fukanzazengi by Dogen says:

The zazen I speak of is not learning meditation. It is simply the Dharma gate of repose and bliss, the practice-realization of totally culminated enlightenment. It is the manifestation of ultimate reality... If you concentrate your effort single-mindedly, that in itself is
  negotiating the Way


user111: Not sure about many religions. I think Hinduism and Jainism have concepts of Nirvana. But they are different from the Buddhist teaching of Nibbana. Anyways, it's so simple in Buddhism. You only need to eliminate craving to attain what Buddhists mean by 'Nibbana'. Read about the "Four Noble Truths".

user86: Nirvana can defined as a peaceful state of mind that is free from craving, anger and mental suffering. 
So answer for, What is required to achieve Nirvana is eliminate all the above things. 

user11911: Nirvana is not a one-time switch... You're in Samsara - BOOM! - you're in Nirvana and for good! It's not like that. 
Nirvana is a momentary experience of freedom and peace. It can ONLY be such as there is nothing else existent but this moment. To realize such peace and freedom, it's helpful to loosen up one's attachment to desirable conditions and rejection of undesirable conditions. In other words, to loosen up your dependence on conditions overall when it comes to happiness and peace.
Through meditation practice and discipline in everyday life, it will become easier and easier to let go of our expectations, assumptions and demands that life go our way. That's not to say we don't make an effort to have favorable conditions in our lives... Not at all. That would be very anti-life and against our basic nature. We all enjoy good things and rightfully so.
But when our desire for good things becomes constant craving and strong attachment to those things, we're screwed because all good things come to an end (and are replaced by "bad things" like loss, old age, sickness and - gulp! - death). There is no peace or happiness in such craving and attachment. And there's no lack of peace or unhappiness in "bad" conditions either. But our normal approach is to loop endlessly through these cycles of craving, clinging and disappointment. It's very tiring and painful.
"Nirvana" is the momentary experience of being free of this endless cycle. It's that simple. And the more you experience this freedom, the less you will care about the changing conditions of your life and be able to flow with all of it. Yet, you are never finished with developing this capacity as it goes very deep.

user142: In Theravadan tradition you need to gain Insight through Vipassana meditation in order to attain Nirvana. That's all! Everytthing else just makes the path to Enlightenment easier or has other benefits like Samatha meditation.

user11839: Nirvana is not an achievement! According to the Buddha there is no path to it because then nirvana becomes an effect of taking that particular path. Also, no practice will lead you to nirvana. Because again, nirvana becomes the effect of the practice. If nirvana is an effect it's not the end of suffering is it? Buddha's only advice was to fully investigate, understand the cause of suffering. According to him understanding of the cause is the ending of suffering. Paths and practices were introduced by monks(not the Buddha) for their survival, existence!

user11897: I am reading a book called What the Buddha Taught by Dr. Walpola Sri  Rahula.
Noble Eightfold Path
The Fourth Noble Truth is 'The Path' (Magga) leading to the cessation of Dukkha (defined in the First Noble Truth as basically anything conditioned or in other words part of dualism; things that are not everlasting)
See other answers that already list the eight divisions/categories.
Five Hinderances
Ponder these.


lustful desires (kāmacchanda)
ill-will, hatred, or anger (vyāpāda)
torpor and languor (thīna-middha)
restlessness and worry (uddhacca-kukkucca)
sceptical doubts (vicikicchā)


Seven Factors of Enlightenment
Meditate on these.


Mindfulness (sati) i.e. to be aware and mindful in all activities and movements both physical and mental.
Investigation and research into the various problems of doctrine (dhamma-vicaya). Included here are all our religious, ethical, and
  philosophical studies, reading, researches, discussions,
  conversations, even attending lectures relating to such doctrinal
  subjects.
Energy (viriya), to work with determination till the end.
Joy (pīti), the quality quite contrary to the pessimistic, gloomy, or melancholic attitude of mind.
Relaxation (passaddhi) of both body and mind. One should not be stiff physically or mentally.
Concentration (samādhi).
Equanimity (upekkhā) i.e. to be able to face life in all its vicissitudes with calm of mind, tranquillity, without disturbance.

To cultivate these qualities the most essential thing is a genuine
  wish, will, or inclination. [...] One may also meditate on such
  subjects as the Five Aggregates investigating the question "What is
  being?" or "What is it that is called I?", or on the Four Noble
  Truths. Study and investigation of those subjects constitute this
  fourth form of meditation, which leads to the realization of Ultimate
  Truth.

Excerpt about the feeling 'I AM'

It is the vague feeling 'I AM' that creates the idea of self which has
  no corresponding reality, and to see this truth is to realize Nirvāna,
  which is not very easy. In the Samyutta-nikāya there is an
  enlightening conversation on this point between a bhikkhu named
  Khemaka and a group of bhikkhus.
These bhikkhus ask Khemaka whether he sees in the Five Aggregates any
  self or anything pertaining to a self. Khemaka relies 'No'. Then the
  bhikkhus say that, if so, he should be an Arahant free from all
  impurities. But Khemaka confesses that though he does not find in the
  Five Aggregates a self, or anything pertaining to self, 'I am not an
  Arahant free from all impurities.' O friends, with regard to the Five
  Aggregates of Attachment, I have a feeling "I AM", but I do not
  clearly see "This is I AM".' Then Khemaka explains that what he calls
  'I AM' is neither matter, sensation, perception, mental formations,
  nor consciousness, nor anything without them. But he has the feeling
  'I AM' with regard to the Five Aggregates, though he could not see
  clearly 'This is I AM'.
He says it is like the smell of a flower: it is neither the smell of
  the petals, nor the color, not of the pollen, but the smell of the
  flower. Khemata further explains that even a person who has attained
  the early stages of realization still retains this feeling 'I AM'. But
  later on, when he progresses further, this feeling of 'I AM'
  altogether disappears, just as the chemical smell of a freshly washed
  cloth disappears after a time when it is kept in a box.
This discussion was so useful and enlightening to them that at the end
  of it, the text says, all of them, including Khemata himself, became
  Arahants free from all impurities, thus finally getting rid of 'I AM'.


user5605: In Buddhism you need to follow the Noble Eight Fold path to attain nirvana. It is further divided into three parts for simplicity - Sila (morality), Samadhi (mental culture) and Panna ( wisdom). 
The noble eight fold path is as below :
Sila (Morality): 1) right speech 2) right action 3) right livelihood
Samadhi (mental culture): 4) right awareness 5) right concentration 6) right efforts 
Panna (wisdom) : 7) right resolve 8) right view
In whichever teaching the components of Noble Eight Fold path is found there you will find source of Nirvana. So you can follow any sect you prefer. But right view is what differs in Buddhism which takes you in right direction. Understanding Buddhism's (right) view of rebirth, karma and three realities of life (impermanence, no soul and suffering) and dependent origination can help understand Nirvana better.

user43: To answer your question let me draw an analogy. What is required to become a professor?
According to Wikipedia, "A professor is a highly accomplished and recognized academic, and the title is in most cases awarded only after decades of scholarly work to senior academics". Being a professor is not a concrete state, it is a label they put on years of hard work, culminating in professional realization.
Similarly, Nirvana is not a concrete state, it is a common name for the condition of a highly accomplished spiritual practitioner. This condition is not something you can contrive knowing the requirements, it is a result of years of personal transformation.
Nirvana can be characterized as condition of having transcended suffering & death. The requirement for this is said to be a complete cessation of Attraction (obsessing over something as desirable), Rejection (obsessing over something as undesirable), and Ignorance (mistaken understanding of how everything works). One of the key components of Ignorance is a deeply lying conviction in existence of substantial self and a tangle of reflexes that grow around that. Much of Mahayana practice is targeted at destroying this belief, not just at conceptual level, but at the level of basic day-to-day instincts.
If we could simplify the requirement for becoming a professor to "complete cessation of ignorance in the field of study one specializes in", we could perhaps make a stretch and define Nirvana as "complete cessation of ego complex, along with negative experiences and behavioral tendencies it generates". As any simplification, this is not entirely accurate: just as becoming a professor requires tons of practical skill and experience outside of the primary field of study, attaining Nirvana requires cessation of all mental and emotional obscurations, a tendency to get stuck on anything, not just on self.
Now, for the purposes of this discussion I'm equating Nirvana with Enlightenment, which depending on a school may or may not be the right thing to do. Specifically in Mahayana, Nirvana is considered a conceptual projection (a shadow of ego so to speak) that has to be transcended as part of awakening to Self-Existing Buddha Nature (=Enlightenment).

113: <p>Nirvana is considered by many religions the pinnacle to strive for.  What do I need to do to achieve Nirvana?  Are there different perceptions of the requirements held by different sects? </p>
 -1: <p>I believe that all Buddhist "sects" would say that there is a path to nirvana. In deed this is the "fourth noble truth", though different "sects" interpret it differently, or at least claim that other "sects" have a different understanding of it. For your purposes, maybe that's what the long history of doctrinal debate is actually about.</p>

<p>I believe that <em>all Buddhists</em> claim that meditation is a prerequisite to nirvana, though that seems to take different forms, with different "sects" vying over e.g. the terms "sudden" and "gradual", and with different instructions and communities.</p>

<p>I've put 'sect' in quotes because I'm going to side with what I understand from soto zen, which I think stresses that we "<a href="http://brightwayzen.org/enlightenment-as-choice-not-a-skill/" rel="nofollow noreferrer">don’t</a> practice zazen in order to get enlightened, we practice being enlightened as we practice zazen". So the fukanzazengi by Dogen says:</p>

<blockquote>
  <p><a href="http://www.zen-deshimaru.com/en/zen/fukanzazengi-eihei-dogen-unabridged-english-translation" rel="nofollow noreferrer">The zazen</a> I speak of is not learning meditation. It is simply the Dharma gate of repose and bliss, the practice-realization of totally culminated enlightenment. It is the manifestation of ultimate reality... If you concentrate your effort single-mindedly, that in itself is
  negotiating the Way</p>
</blockquote>
 111: <p>Not sure about many religions. I think Hinduism and Jainism have concepts of Nirvana. But they are different from the Buddhist teaching of Nibbana. Anyways, it's so simple in Buddhism. You only need to eliminate craving to attain what Buddhists mean by 'Nibbana'. Read about the "Four Noble Truths".</p>
 86: <p>Nirvana can defined as a peaceful state of mind that is free from craving, anger and mental suffering. </p>

<p>So answer for, What is required to achieve Nirvana is eliminate all the above things. </p>
 11911: <p>Nirvana is not a one-time switch... You're in Samsara - BOOM! - you're in Nirvana and for good! It's not like that. </p>

<p>Nirvana is a momentary experience of freedom and peace. It can ONLY be such as there is nothing else existent but this moment. To realize such peace and freedom, it's helpful to loosen up one's attachment to desirable conditions and rejection of undesirable conditions. In other words, to loosen up your dependence on conditions overall when it comes to happiness and peace.</p>

<p>Through meditation practice and discipline in everyday life, it will become easier and easier to let go of our expectations, assumptions and demands that life go our way. That's not to say we don't make an effort to have favorable conditions in our lives... Not at all. That would be very anti-life and against our basic nature. We all enjoy good things and rightfully so.</p>

<p>But when our desire for good things becomes constant craving and strong attachment to those things, we're screwed because all good things come to an end (and are replaced by "bad things" like loss, old age, sickness and - gulp! - death). There is no peace or happiness in such craving and attachment. And there's no lack of peace or unhappiness in "bad" conditions either. But our normal approach is to loop endlessly through these cycles of craving, clinging and disappointment. It's very tiring and painful.</p>

<p>"Nirvana" is the momentary experience of being free of this endless cycle. It's that simple. And the more you experience this freedom, the less you will care about the changing conditions of your life and be able to flow with all of it. Yet, you are never finished with developing this capacity as it goes very deep.</p>
 142: <p>In Theravadan tradition you need to gain Insight through Vipassana meditation in order to attain Nirvana. That's all! Everytthing else just makes the path to Enlightenment easier or has other benefits like Samatha meditation.</p>
 11839: <p>Nirvana is not an achievement! According to the Buddha there is no path to it because then nirvana becomes an effect of taking that particular path. Also, no practice will lead you to nirvana. Because again, nirvana becomes the effect of the practice. If nirvana is an effect it's not the end of suffering is it? Buddha's only advice was to fully investigate, understand the cause of suffering. According to him understanding of the cause is the ending of suffering. Paths and practices were introduced by monks(not the Buddha) for their survival, existence!</p>
 11897: <p>I am reading a book called <em>What the Buddha Taught</em> by Dr. Walpola Sri  Rahula.</p>

<h1>Noble Eightfold Path</h1>

<p>The Fourth Noble Truth is 'The Path' (Magga) leading to the cessation of Dukkha (defined in the First Noble Truth as basically anything conditioned or in other words part of dualism; things that are not everlasting)</p>

<p>See other answers that already list the eight divisions/categories.</p>

<h1>Five Hinderances</h1>

<p>Ponder these.</p>

<blockquote>
  <ol>
  <li>lustful desires (kāmacchanda)</li>
  <li>ill-will, hatred, or anger (vyāpāda)</li>
  <li>torpor and languor (thīna-middha)</li>
  <li>restlessness and worry (uddhacca-kukkucca)</li>
  <li>sceptical doubts (vicikicchā)</li>
  </ol>
</blockquote>

<h1>Seven Factors of Enlightenment</h1>

<p>Meditate on these.</p>

<blockquote>
  <ol>
  <li>Mindfulness (sati) i.e. to be aware and mindful in all activities and movements both physical and mental.</li>
  <li>Investigation and research into the various problems of doctrine (dhamma-vicaya). Included here are all our religious, ethical, and
  philosophical studies, reading, researches, discussions,
  conversations, even attending lectures relating to such doctrinal
  subjects.</li>
  <li>Energy (viriya), to work with determination till the end.</li>
  <li>Joy (pīti), the quality quite contrary to the pessimistic, gloomy, or melancholic attitude of mind.</li>
  <li>Relaxation (passaddhi) of both body and mind. One should not be stiff physically or mentally.</li>
  <li>Concentration (samādhi).</li>
  <li>Equanimity (upekkhā) i.e. to be able to face life in all its vicissitudes with calm of mind, tranquillity, without disturbance.</li>
  </ol>
  
  <p>To cultivate these qualities the most essential thing is a genuine
  wish, will, or inclination. [...] One may also meditate on such
  subjects as the Five Aggregates investigating the question "What is
  being?" or "What is it that is called I?", or on the Four Noble
  Truths. Study and investigation of those subjects constitute this
  fourth form of meditation, which leads to the realization of Ultimate
  Truth.</p>
</blockquote>

<h1>Excerpt about the feeling 'I AM'</h1>

<blockquote>
  <p>It is the vague feeling 'I AM' that creates the idea of self which has
  no corresponding reality, and to see this truth is to realize Nirvāna,
  which is not very easy. In the Samyutta-nikāya there is an
  enlightening conversation on this point between a bhikkhu named
  Khemaka and a group of bhikkhus.</p>
  
  <p>These bhikkhus ask Khemaka whether he sees in the Five Aggregates any
  self or anything pertaining to a self. Khemaka relies 'No'. Then the
  bhikkhus say that, if so, he should be an Arahant free from all
  impurities. But Khemaka confesses that though he does not find in the
  Five Aggregates a self, or anything pertaining to self, 'I am not an
  Arahant free from all impurities.' O friends, with regard to the Five
  Aggregates of Attachment, I have a feeling "I AM", but I do not
  clearly see "This is I AM".' Then Khemaka explains that what he calls
  'I AM' is neither matter, sensation, perception, mental formations,
  nor consciousness, nor anything without them. But he has the feeling
  'I AM' with regard to the Five Aggregates, though he could not see
  clearly 'This is I AM'.</p>
  
  <p>He says it is like the smell of a flower: it is neither the smell of
  the petals, nor the color, not of the pollen, but the smell of the
  flower. Khemata further explains that even a person who has attained
  the early stages of realization still retains this feeling 'I AM'. But
  later on, when he progresses further, this feeling of 'I AM'
  altogether disappears, just as the chemical smell of a freshly washed
  cloth disappears after a time when it is kept in a box.</p>
  
  <p>This discussion was so useful and enlightening to them that at the end
  of it, the text says, all of them, including Khemata himself, became
  Arahants free from all impurities, thus finally getting rid of 'I AM'.</p>
</blockquote>
 5605: <p>In Buddhism you need to follow the Noble Eight Fold path to attain nirvana. It is further divided into three parts for simplicity - Sila (morality), Samadhi (mental culture) and Panna ( wisdom). </p>

<p>The noble eight fold path is as below :
Sila (Morality): 1) right speech 2) right action 3) right livelihood
Samadhi (mental culture): 4) right awareness 5) right concentration 6) right efforts 
Panna (wisdom) : 7) right resolve 8) right view</p>

<p>In whichever teaching the components of Noble Eight Fold path is found there you will find source of Nirvana. So you can follow any sect you prefer. But right view is what differs in Buddhism which takes you in right direction. Understanding Buddhism's (right) view of rebirth, karma and three realities of life (impermanence, no soul and suffering) and dependent origination can help understand Nirvana better.</p>
 43: <p>To answer your question let me draw an analogy. What is required to become a professor?
According to Wikipedia, "A professor is a highly accomplished and recognized academic, and the title is in most cases awarded only after decades of scholarly work to senior academics". Being a professor is not a concrete state, it is a label they put on years of hard work, culminating in <em>professional realization</em>.</p>

<p>Similarly, Nirvana is not a concrete state, it is a common name for the condition of a highly accomplished spiritual practitioner. This condition is not something you can contrive knowing the requirements, it is a result of years of personal transformation.</p>

<p>Nirvana can be characterized as condition of having transcended suffering &amp; death. The requirement for this is said to be a complete cessation of Attraction (obsessing over something as desirable), Rejection (obsessing over something as undesirable), and Ignorance (mistaken understanding of how everything works). One of the key components of Ignorance is a deeply lying conviction in existence of <em>substantial self</em> and a tangle of reflexes that grow around that. Much of Mahayana practice is targeted at destroying this belief, not just at conceptual level, but at the level of basic day-to-day instincts.</p>

<p>If we could simplify the requirement for becoming a professor to "complete cessation of ignorance in the field of study one specializes in", we could perhaps make a stretch and define Nirvana as "complete cessation of ego complex, along with negative experiences and behavioral tendencies it generates". As any simplification, this is not entirely accurate: just as becoming a professor requires tons of practical skill and experience outside of the primary field of study, attaining Nirvana requires cessation of all mental and emotional obscurations, a tendency to get stuck on anything, not just on self.</p>

<p>Now, for the purposes of this discussion I'm equating Nirvana with Enlightenment, which depending on a school may or may not be the right thing to do. Specifically in Mahayana, Nirvana is considered a conceptual projection (a shadow of ego so to speak) that has to be transcended as part of awakening to Self-Existing Buddha Nature (=Enlightenment).</p>
