user11541: According to some there are 5 principal types of meditations:

Metta-Bhavana 
Karuna-Bhavana
Mudita Bhavana
Asubha Bhavana 
Upekka Bhavana

I couldn't find any link which could support the above mentioned meditation theory.
So my questions are:
Is it true that there are 5 principal types of Meditations?
Can anyone provide me the original links where Buddha lays down the above mentioned 5 types of meditation?

user471: As stated by Sankha, there are only two types of meditation - concentration (samatha) and insight (vipassana). Even these two need not be mutually exclusive.
For concentration meditation, you can have various objects to concentrate on, like the breath (anapanasati), or loving kindness (metta) or unattractiveness (asubha) or any of the ten kasinas. The objective is to cultivate the jhana states.
For insight meditation, breath (anapanasati) is generally used, but the focus here is to observe the nature of reality based on the four foundations of mindfulness. So, even here, it can be on the body, feelings, thoughts or the different mental objects or dhammas, but without an intentional choice of an object of concentration.
Both are not mutually exclusively. For e.g. if you have a camera, you can zoom in and change other settings on your subject of focus, in order to get the best, sharpest and clearest photo of the chosen subject. That's like samatha.
But if you move your camera around to find good subjects to photograph, then that's like vipassana. The four foundations of mindfulness show you what subjects are good to observe, just like in photography you have landscape, animals, portraits etc. Eventually you need to use both techniques to get the best photo of the best subject.
It makes sense to me that learning how to focus your camera first (samatha), is preferred, before learning what kind of subjects to photograph (vipassana). If you try to take photos of your subjects before you learn how to focus your camera, your photos will turn out blurry or too dark or too bright etc (obstruction by the five hindrances). But in the first phase of learning how to focus your camera, you might focus on unimportant subjects like your toes (kasinas).
Another analogy is physics and mathematics. You want to study physics (vipassana) to learn about the nature of reality. You may be very eager to do so. But it would be unpleasant and difficult to learn physics in detail, before mastering math (samatha) first. You need to study math and master it to a certain degree, then you can use it to study physics smoothly and pleasantly.
In the first phase of studying math, you might use it to calculate unimportant things (kasinas) like using algebraic terms like x and y without having any specific meaning, for the sake of performing integration or differentiation on them. When you use it to study physics, then you can differentiate velocity v over time t, to get acceleration a.

user11541: I have found the reference to the 4 of the 5 kinds of contemplation mentioned in the question. They are taken from Visuddhimagga sanna(or sanne??).
To quote -

Metta in the Buddha's teaching finds its place as the first of four
  kinds of contemplation designed to develop a sound pacific
  relationship to other living beings. The four are: metta, which will
  be rendered henceforward by "loving-kindness," karuna, which is
  "compassion" or "pity," mudita which is "gladness at others' success,"
  and upekkha, which is "onlooking equanimity." These four are called
  Divine Abidings (brahma-vihara), perhaps because whoever can maintain
  any one of them in being for even a moment has lived for that moment
  as do the Highest Gods (the Brahma Deva).

To quote further from the document:

But first, before coming to these discourses, some details from the
  meditation manual, the Visuddhimagga or "Path of Purification," will
  not be out of place.
Metta (loving-kindness) is defined as follows: "Loving-kindness has
  the mode of friendliness for its characteristic. Its natural function
  is to promote friendliness. It is manifested as the disappearance of
  ill-will. Its footing is seeing with kindness. When it succeeds it
  eliminates ill-will. When it fails it degenerates into selfish
  affectionate desire."
The Visuddhimagga recommends going to some quiet place, where one can
  sit down in a comfortable position. Then, before starting the actual
  meditation, it is helpful to consider the dangers in hate and the
  benefits offered by forbearance: for it is a purpose of this
  meditation to displace hate by forbearance, and besides, one cannot
  avoid dangers one has not come to see or cultivate benefits one does
  not yet know.

Buddha says the following about the four sublime states:

I. Here, monks, a disciple dwells pervading one direction with his
  heart filled with loving-kindness, likewise the second, the third, and
  the fourth direction; so above, below and around; he dwells pervading
  the entire world everywhere and equally with his heart filled with
  loving-kindness, abundant, grown great, measureless, free from enmity
  and free from distress.
II. Here, monks, a disciple dwells pervading one direction with his
  heart filled with compassion, likewise the second, the third and the
  fourth direction; so above, below and around; he dwells pervading the
  entire world everywhere and equally with his heart filled with
  compassion, abundant, grown great, measureless, free from enmity and
  free from distress.
III. Here, monks, a disciple dwells pervading one direction with his
  heart filled with sympathetic joy, likewise the second, the third and
  the fourth direction; so above, below and around; he dwells pervading
  the entire world everywhere and equally with his heart filled with
  sympathetic joy, abundant, grown great, measureless, free from enmity
  and free from distress.
IV. Here, monks, a disciple dwells pervading one direction with his
  heart filled with equanimity, likewise the second, the third and the
  fourth direction; so above, below and around; he dwells pervading the
  entire world everywhere and equally with his heart filled with
  equanimity, abundant, grown great, measureless, free from enmity and
  free from distress.

The fifth one (Ashubh Bhawana contemplation) can be found here. 

user254: Yes and no: i.e., "Yes, there are 5"; and, "No, there are more than 5".
4 of the ones you listed are to bring into being what are known as the 4 "Brahma-viharas" (of which, metta-bhavana may be the most famous).
I'm not sure that types of meditation are detailed in the suttas (some are). Various types may be detailed in more detail in the 5th century Path of Purification (Visuddhimagga). If I were looking for references to them in the suttas I think I'd start search by searching in accesstoinsight.org (searching for "Brahma-viharas" and/or "metta" and so on).
The fifth one, Asubha, is meant as an antidote to lust: and so, for example, it's contemplation of the foulness of the body (e.g. the Asubha Sutta, and one of the meditation types mentioned in the Satipatthana Sutta).
Other principal types include meditation intended for insight, concentration, mindfulness, tranquility, detachment. They're named things like "Vipassana", and "Anapanasati" (Anapanasati Sutta)
Samana Johann linked to a reference which lists "40 types" (in reply to another question of yours).
The ones I've listed are from Theravada (Mahayana may have others).

user111: There are only 2 types of meditations. 

Samatha(Concentration)
Vipassana(Insight)

All those 5 meditations you have mentioned and many more come under Samatha meditation. More on Samatha vs Vipassana...

11541: <p><a href="https://books.google.co.in/books?id=gM8YDQAAQBAJ&amp;pg=PT343&amp;lpg=PT343&amp;dq=meditate%20on%20love%20pity%20joy%20impurity%20serenity%20buddha&amp;source=bl&amp;ots=K2zrlhZST_&amp;sig=_HpLmLFn-t84vTK_JEW-YRp-1GQ&amp;hl=en&amp;sa=X&amp;ved=0ahUKEwjepfiw9dTWAhXBr48KHdNRCdUQ6AEIOzAI#v=onepage&amp;q=meditate%20on%20love%20pity%20joy%20impurity%20serenity%20buddha&amp;f=false" rel="nofollow noreferrer">According to some</a> there are 5 principal types of meditations:</p>

<ol>
<li>Metta-Bhavana </li>
<li>Karuna-Bhavana</li>
<li>Mudita Bhavana</li>
<li>Asubha Bhavana </li>
<li>Upekka Bhavana</li>
</ol>

<p>I couldn't find any link which could support the above mentioned meditation theory.</p>

<p>So my questions are:</p>

<p>Is it true that there are 5 principal types of Meditations?</p>

<p>Can anyone provide me the original links where Buddha lays down the above mentioned 5 types of meditation?</p>
 471: <p>As stated by Sankha, there are only two types of meditation - concentration (<a href="https://en.wikipedia.org/wiki/Samatha" rel="nofollow noreferrer">samatha</a>) and insight (<a href="https://en.wikipedia.org/wiki/Vipassan%C4%81" rel="nofollow noreferrer">vipassana</a>). Even these two need not be mutually exclusive.</p>

<p>For concentration meditation, you can have various objects to concentrate on, like the breath (anapanasati), or loving kindness (metta) or unattractiveness (asubha) or any of the <a href="https://en.wikipedia.org/wiki/Kasina" rel="nofollow noreferrer">ten kasinas</a>. The objective is to cultivate the <a href="http://www.accesstoinsight.org/ptf/dhamma/sacca/sacca4/samma-samadhi/jhana.html" rel="nofollow noreferrer">jhana states</a>.</p>

<p>For insight meditation, breath (anapanasati) is generally used, but the focus here is to observe the nature of reality based on the <a href="http://www.accesstoinsight.org/lib/authors/nyanasatta/wheel019.html" rel="nofollow noreferrer">four foundations of mindfulness</a>. So, even here, it can be on the body, feelings, thoughts or the different mental objects or dhammas, but without an intentional choice of an object of concentration.</p>

<p>Both are not mutually exclusively. For e.g. if you have a camera, you can zoom in and change other settings on your subject of focus, in order to get the best, sharpest and clearest photo of the chosen subject. That's like samatha.</p>

<p>But if you move your camera around to find good subjects to photograph, then that's like vipassana. The four foundations of mindfulness show you what subjects are good to observe, just like in photography you have landscape, animals, portraits etc. Eventually you need to use both techniques to get the best photo of the best subject.</p>

<p>It makes sense to me that learning how to focus your camera first (samatha), is preferred, before learning what kind of subjects to photograph (vipassana). If you try to take photos of your subjects before you learn how to focus your camera, your photos will turn out blurry or too dark or too bright etc (obstruction by the five hindrances). But in the first phase of learning how to focus your camera, you might focus on unimportant subjects like your toes (kasinas).</p>

<p>Another analogy is physics and mathematics. You want to study physics (vipassana) to learn about the nature of reality. You may be very eager to do so. But it would be unpleasant and difficult to learn physics in detail, before mastering math (samatha) first. You need to study math and master it to a certain degree, then you can use it to study physics smoothly and pleasantly.</p>

<p>In the first phase of studying math, you might use it to calculate unimportant things (kasinas) like using algebraic terms like x and y without having any specific meaning, for the sake of performing integration or differentiation on them. When you use it to study physics, then you can differentiate velocity v over time t, to get acceleration a.</p>
 11541: <p>I have found the <a href="http://www.accesstoinsight.org/lib/authors/nanamoli/wheel007.html" rel="nofollow noreferrer">reference</a> to the 4 of the 5 kinds of contemplation mentioned in the question. They are taken from <strong>Visuddhimagga</strong> sanna(or sanne??).
To quote -</p>

<blockquote>
  <p>Metta in the Buddha's teaching finds its place as the first of four
  kinds of contemplation designed to develop a sound pacific
  relationship to other living beings. The four are: metta, which will
  be rendered henceforward by "loving-kindness," karuna, which is
  "compassion" or "pity," mudita which is "gladness at others' success,"
  and upekkha, which is "onlooking equanimity." These four are called
  Divine Abidings (brahma-vihara), perhaps because whoever can maintain
  any one of them in being for even a moment has lived for that moment
  as do the Highest Gods (the Brahma Deva).</p>
</blockquote>

<p>To quote further from the document:</p>

<blockquote>
  <p>But first, before coming to these discourses, some details from the
  meditation manual, the Visuddhimagga or "Path of Purification," will
  not be out of place.</p>
  
  <p>Metta (loving-kindness) is defined as follows: "Loving-kindness has
  the mode of friendliness for its characteristic. Its natural function
  is to promote friendliness. It is manifested as the disappearance of
  ill-will. Its footing is seeing with kindness. When it succeeds it
  eliminates ill-will. When it fails it degenerates into selfish
  affectionate desire."</p>
  
  <p>The Visuddhimagga recommends going to some quiet place, where one can
  sit down in a comfortable position. Then, before starting the actual
  meditation, it is helpful to consider the dangers in hate and the
  benefits offered by forbearance: for it is a purpose of this
  meditation to displace hate by forbearance, and besides, one cannot
  avoid dangers one has not come to see or cultivate benefits one does
  not yet know.</p>
</blockquote>

<p>Buddha says the following about the four <a href="http://www.accesstoinsight.org/lib/authors/nyanaponika/wheel006.html#basic" rel="nofollow noreferrer">sublime states</a>:</p>

<blockquote>
  <p>I. Here, monks, a disciple dwells pervading one direction with his
  heart filled with loving-kindness, likewise the second, the third, and
  the fourth direction; so above, below and around; he dwells pervading
  the entire world everywhere and equally with his heart filled with
  loving-kindness, abundant, grown great, measureless, free from enmity
  and free from distress.</p>
  
  <p>II. Here, monks, a disciple dwells pervading one direction with his
  heart filled with compassion, likewise the second, the third and the
  fourth direction; so above, below and around; he dwells pervading the
  entire world everywhere and equally with his heart filled with
  compassion, abundant, grown great, measureless, free from enmity and
  free from distress.</p>
  
  <p>III. Here, monks, a disciple dwells pervading one direction with his
  heart filled with sympathetic joy, likewise the second, the third and
  the fourth direction; so above, below and around; he dwells pervading
  the entire world everywhere and equally with his heart filled with
  sympathetic joy, abundant, grown great, measureless, free from enmity
  and free from distress.</p>
  
  <p>IV. Here, monks, a disciple dwells pervading one direction with his
  heart filled with equanimity, likewise the second, the third and the
  fourth direction; so above, below and around; he dwells pervading the
  entire world everywhere and equally with his heart filled with
  equanimity, abundant, grown great, measureless, free from enmity and
  free from distress.</p>
</blockquote>

<p>The fifth one (Ashubh Bhawana contemplation) can be found <a href="http://www.accesstoinsight.org/tipitaka/an/an04/an04.163.than.html" rel="nofollow noreferrer">here</a>. </p>
 254: <p>Yes and no: i.e., "Yes, there are 5"; and, "No, there are more than 5".</p>

<p>4 of the ones you listed are to bring into being what are known as the 4 "Brahma-viharas" (of which, metta-bhavana may be the most famous).</p>

<p>I'm not sure that types of meditation are detailed in the suttas (some are). Various types may be detailed in more detail in the 5th century Path of Purification (Visuddhimagga). If I were looking for references to them in the suttas I think I'd start search by searching in accesstoinsight.org (searching for "Brahma-viharas" and/or "metta" and so on).</p>

<p>The fifth one, Asubha, is meant as an antidote to lust: and so, for example, it's contemplation of the foulness of the body (e.g. the <a href="http://www.accesstoinsight.org/tipitaka/an/an04/an04.163.than.html" rel="nofollow noreferrer">Asubha Sutta</a>, and one of the meditation types mentioned in the <a href="http://www.accesstoinsight.org/tipitaka/mn/mn.010.than.html" rel="nofollow noreferrer">Satipatthana Sutta</a>).</p>

<p>Other principal types include meditation intended for insight, concentration, mindfulness, tranquility, detachment. They're named things like "Vipassana", and "Anapanasati" (<a href="http://www.accesstoinsight.org/tipitaka/mn/mn.118.than.html" rel="nofollow noreferrer">Anapanasati Sutta</a>)</p>

<p>Samana Johann <a href="https://buddhism.stackexchange.com/a/23011/254">linked to a reference</a> which lists "40 types" (in reply to another question of yours).</p>

<p>The ones I've listed are from Theravada (Mahayana may have others).</p>
 111: <p>There are only 2 types of meditations. </p>

<ol>
<li>Samatha(Concentration)</li>
<li>Vipassana(Insight)</li>
</ol>

<p>All those 5 meditations you have mentioned and many more come under Samatha meditation. <a href="https://buddhism.stackexchange.com/a/3562/111">More on Samatha vs Vipassana...</a></p>
