You can star repositories to keep track of projects you find interesting and discover similar projects in your news feed.
Starring a repository makes it easy to find again later. You can see all the repositories you have starred by going to your stars page. For more information on interacting with your starred repositories, see "Managing your stars."
You can star repositories to discover similar projects on GitHub. When you star repositories, GitHub may recommend similar projects in the discovery view of your news feed. For more information, see "Finding open source projects on GitHub."
Starring a repository also shows appreciation to the repository maintainer for their work. Many of GitHub's repository rankings depend on the number of stars a repository has. For example, repositories can be sorted and searched based on their star count. For more information, see "Searching for repositories." In addition, Explore shows popular repositories based on the number of stars they have.