In Git, rebase is a command that allows developers to integrate changes from one branch onto another by replaying changes from one line of work onto another in the order they were introduced. This is different from merge, which takes the endpoints and merges them together.

When a developer runs rebase, Git creates a whole new series of commits, using the current set of commits as hints. In other words, it calculates what the changes would have looked like if they had started making them from the point they are rebasing on to. After the rebase, the developer might need to re-test their changes and could possibly have a few conflicts.

Some reasons why developers use rebase include:

• Maintaining a linear project history
• Pushing a single commit or a small number of commits developed in a short time frame
• Cleaning up a messy history before merging a feature branch into main

Its important to note that rebase is a destructive operation, meaning that if it is not applied correctly, committed work could be lost and/or the consistency of other developers repositories could be broken. Therefore, its recommended to only rebase commits that have never left the developers own computer or have been pushed but that no one else has based commits from.