Should I merge all commits from an experimental branch or only the valid one?

Question

I am new to git and trying to understand the best practices about commits and merging.
Of course you shouldn't commit buggy changes to the master branch, and from what I understand you should create new branches for features / bug fixes in your project.

After testing how merging works, I see that when merging some branch B with branch A, branch A gets all previous commits of branch B in its log, but isn't that problematic if you are merging some experimental branch into your master branch ?
Because then it means that your master branch has in its history commits from experimental branch that were buggy, is this ok anyway or is it a common practice to exclude those commits when merging to master ?

Answer 1

Usually, you would squash your commits into one commit before transferring them to the care of someone else.

The reason is that the intermediate stages of your work are of interest to you while that work isn't finished; you might want to redo something, reverse a decision on one point, understand what the hell you can have been thinking on another point, etc.

The repository owner is much less likely to be interested in the intermediate steps you took in order to resolve a problem or to add functionality. They, and their clients, usually either want all of your work or none of it.

As an added bonus the commit log of the master branch becomes much easier to read if it's a list of meaningful changes to the code base rather than of all changes ever made.