All of the configurations and settings in Linux are saved in text files. Even though you most often can edit configurations through the graphical interface, you may occasionally have to edit them by hand. Gedit is the default Ubuntu text editor, which you can launch by clicking Applications->Accessories->Text Editor on the desktop menu system.
At times in this guide, Gedit is run from the command line using gksudo, which runs Gedit with administrative privileges, in order to modify configuration files.
If you need to use a text editor from the command line, you can use nano, which is a simple to use text editor. When running it from the command line, always use the following command, which ensures that the editor will not introduce line breaks:
For more information about how to use nano, refer to the guide on the wiki.
There are also quite a few other terminal-based editors available in Ubuntu, popular ones include VIM and Emacs (the pros and cons of each are cause for much friendly debate within the Linux community). These are often more complex to use than nano, but are also more powerful.