Commit only part of a file in Git

Question

When I make changes to a file in Git, how can I commit only some of the changes?

For example, how could I commit only 15 lines out of 30 lines that have been changed

Answer 1

For those who use Git Extensions:

In the Commit window, select the file you want to partially commit, then select the text you want to commit in the right pane, then right-click on the selection and choose 'Stage selected lines' from the context menu.