l3.txt

Using a remote repository:
This allows other people to view and contribute to your work. Also, if your computer breaks and you lose your local data, your repository will still be available online.

Pulling changes manually:
Perhaps you are making changes to your local repository and not ready to update it. Manually pulling changes makes sure that you update your local repository only when you are ready.

Comparing forks, clones, and branches:
A branch is a chain of commits. It is located inside a single repository, which may have multiple branches.
A clone is a copy of another repository. You can clone from GitHub to local or between two local locations.
A fork is a special version of a clone that you can perform on GitHub. You can fork someone else's project to make your own version.

Benefits of having the last known state of remote branches:
This allows you to update your local repository with changes from the remote repository only when you need to with "fetch". These fetched changes will not disturb your local repository or your working directory.

Collaborating without git and github:
Without git, I would probably use Dropbox to backup and access previous versions of my code, which is less helpful than git's commit log with commit messages. Without github, it would be more difficult to share code with others. Anyone can fork, contribute to, or comment on your project. 

Making changes in a separate branch rather than master:
This ensures that you will not introduce a bug into master. This also allows you to submit a pull request, so others can review your changes before they are merged.