The git commit command creates a commit, which is like a snapshot of your repository. These commits are snapshots of your entire repository at specific times. You should make new commits often, based around logical units of change. Over time, commits should tell a story of the history of your repository and how it came to be the way that it currently is. Commits include lots of metadata in addition to the contents and message, like the author, timestamp, and more.
Commits are the building blocks of "save points" within Git's version control.
git commit -m "update the README.md with link to contributing guide"