Keyword research

Keyword research is a practice search engine optimization (SEO) professionals use to find and research search terms that users enter into search engines when looking for products, services or general information. Keywords are related to queries, which are asked by users in search engines. There are three types of queries : 1. Navigational Search Queries 2. Informational Search Quearies 3. Transactional Search Queries. Search engine optimization professionals first research keywords, and then align web pages with these keywords to achieve better rankings in search engines. Once they find a niche keyword, they expand on it to find similar keywords. Keyword suggestion tools usually aid the process, like the Google Ads Keyword Planner, which offers a thesaurus and alternative keyword suggestions. Google's first party data also aids this research through the likes of Google autocomplete or People Also Ask. 
Importance of research.
Keyword research.
The objective of keyword research is to generate, with good precision and recall, a large number of terms that are highly relevant yet non-obvious to the given input keyword. The process of keyword research involves brainstorming and the use of keyword research tools. To achieve the best SEO results, it is important to optimize a website's content as well as backlinks for the most relevant keywords. It is good practice to search for related keywords that have low competition and still a high number of searches. This makes it easier to achieve a higher rank in search engines which usually results in higher web traffic. The downside of this practice is that the website is optimized for alternative keywords instead of the main keyword; main keywords might be very difficult to rank due to high competition. There are three essential concepts to consider when conducting keyword research. Good keywords are closely related to the subject of the website. Most search engines use an internal quality system to check website relevance related to possible keywords, a non-relevant keyword is unlikely to rank well for a website. Good keywords that are highly competitive are less likely to rank in the top. Keywords that have no monthly searches are believed to generate little to no traffic and therefore of little value for SEO. Keyword stuffing in a web page should be avoided.
Types of keywords.
Keywords are divided into two primary groups based on search volume. 
Research examples.
A very popular and highly competitive keyword on Google search engine is "making money." It has 4,860,000,000 search results, meaning that billions of websites are relevant or competing for that keyword. Keyword research starts with finding all possible word combinations that are relevant to the "making money" keyword. For example, a keyword "acquiring money" has significantly fewer search results, only 116,000,000, but it has the same meaning as "making money." Another way is to be more specific about a keyword by adding additional filters. For example the keyword "making money online from home in Canada" is less competitive on a global scale and therefore easier to rank for. Furthermore, keywords also have various intents which can affect whether the marketer would want to target that keyword. Multiple tools are available (both free and commercial) to find keywords and analyze them.
Keyword research tools.
Google Ads Keyword Planner.
Google offers free tools to do some basic keyword analysis. All the results are based on data of the Google search engine.
Google recently released an update to the Google keyword planner and changes some of its policy by which the first campaign must be set in order to get the keyword planner back. This is a type of Google Ads account that is used by agencies and consultants to manage many different advertising accounts.
Features of Google Ads Keyword Planner: 
Limitations of Google Ads Keyword Planner:
Google Trends.
Google trend is a free research tool provided by Google to see the trends of any particular keyword. It particularly helps to visualize and compare the data from Google searches. The tool uses graphs to showcase the trend of data over time. It allows users to compare multiple keyword trends to find out which keywords are popular than others in particular regions at a particular time.
Google Suggest.
Google has introduced Google Suggest in 2012. Google Suggest is typically used as a live feature while a user is typing a search phrase into the browser or Google website. Google Suggest uses the organic search input of billions of users and try to "guess" that way what a user might be searching for even before he completed entering the query or all the words of a keyword phrase.
This makes Google Suggest a relevant source for keyword research, it contains a large number of organic keywords very closely related to a full or partial keyword and can be used to find additional most searched appending keywords that make the whole keyword less competitive. Google Suggest can be researched through the Google Search website or through a compatible browser for a small number of keywords but also in large scale using free scraper tools.
Bing Ads Keyword Planner.
The Bing Ads Keyword Planner provides keyword and ad group suggestions and shows average monthly search volume trends, relative competition and suggested bids. Features of Bing Keyword Planner:
Limitations of Bing Ads Keyword Planner:
ahrefs Keyword Explorer.
The ahrefs Keyword explorer suggest all related keywords on putting the main keyword in its search bar. This tool helps to identify the newly discovered keywords and number of search being done for them it also tell the difficulty level as per the number of website using the same keyword to rank and different criteria.