The Like Button is a social feature launched by Facebook in 2009. As you can read on the Facebook Help Center, it enables users to interact with other users' content.

Clicking Like below a post on Facebook is a way to let people know that you enjoy it without leaving a comment. Just like a comment, anyone who can see the post can see that you liked it.

After Facebook Like Button success, other social media like Instagram (a heart-shaped button), Twitter (a star-shaped button), and LinkedIn introduced a like button as a simple and immediate reaction to any kind of content.