Users on the GitHub website are able to "star" other people's repositories, thereby saving them in their list of Starred Repos. Some people use "stars" to indicate that they like a project, other people use them as bookmarks so they can follow what's going on with the repo later.
GitHub Stars are an easy metric to keep track of, and I've used them to measure how popular an open source project is. I admit to sometimes even using Stars to determine how battle-tested a repo is, under the assumption that a repo that has received more Stars must have received more use.
However, there are three limitations I noticed with GitHub stars (which makes my current approach to handling them pretty dubious):
- It is easy to create fake accounts on GitHub that can star repos. This can allow you to boost your metrics pretty easily, although you do not want to be obvious when doing them, lest the accounts get detected and deleted. (You can google for "buy GitHub stars" for those that are lazy technically). While you can use fake accounts to star your own repos, you may also want to star other people's repos to avoid leaving a paper trail. And since you don't want to be running all these fake accounts manually, you want to create bots and...you get the picture.
- GitHub Stars may be "juiced" by media attention, which is temporary and not actually based on sustained popularity. This is from personal experience -- after publicizing a fork of an my open source repo on Hacker News, I received some stars, but no corresponding increase in use of my fork. It's possible that a few people were interested in my repo, starred it, and then either never found an actual use case for my fork or promptly forgot about it later on.
- You can star a Repo for any reason. GitHub doesn't care. It merely notes that someone pressed the Star button and that's all. You can guess why it's starred (someone likes it or wants to look at it later), but other reasons are equally plausible (they are bored at work and like starring random repos, they want to star a repo of a friend of theirs).
I'm sure that metric means something. I'm not sure what though. What do GitHub Stars measure, and how should I use them to better understand the vitality/success/popularity of an open source project?
Any answer to this question should be either evidence-based or research-based.