It can be important to developers and administrators to be able to see the line numbers of files they are editing, and gedit is a quick and easy way to edit files without having to load bigger tools – the only problem is that gedit doesn't have line numbering enabled by default.
You might not be aware of this, but enabling line-numbers in gedit is relatively simple. You just open edit and then preferences, then check the box named Display line numbers.
You may also want to play around with two other interesting options, the Highlight current line and Highlight matching brackets options. What they do should be more or less self-explanatory.