What is the main purpose of using keyword in SEO?
 

It's very urgent to know.

Keyword is a single word, and while a combination of those keywords makes phrases. These keywords or phrases are used by the search engines to populate the subjects over the internet. Search engine stores keywords in the database, and when search is done, it will come up with the best possible match

The keywords or phrases used by the search engines to populate the subject over the internet

User search through the keywords in search engine. when we type any keyword on the search engine then the Search engine returns the result related to that products.