Committing Changes
A commit persists all staged changes in your local repository.
Remember: Only staged changes...
...will be included in a commit. Changes that you have not staged will simply remain as local modifications in your working copy - waiting to be either staged & committed later or discarded.

Tower's commit area expands as soon as you click into the commit message subject textfield ("Short Commit Summary"). Alternatively, you can press CTRL + ⇧ + C from anywhere and directly start typing your commit message.
The
button is enabled as soon as both...- a commit subject was entered (filling the "Extended Description" textfield is optional) and
- staged changes are present.
Checking the
option automatically appends your name at the end of the commit's message.Changing Your Last Commit
The Amend option allows you to change your very last commit. Amending rewrites the commit history so that you will not be able to see that the commit was changed at all.
You can add additional changes to your last commit or just modify its message (or both). When checking the amend option in the commit dialog, Tower prefills the message textfield with your last message.
Use Amend with Care!
Be careful when using the amend option: don't amend commits that you've already pushed to a remote repository!
User Profiles

User Profiles are templates that allow you to quickly set or switch your committer identity.
Read more about how to add, manage and use User Profiles.