Have you ever used Notepad? It's very simple, which is good. However, it lacks the power and features of more advanced text editors.
Notepad++ is a free and very powerful text editor. Here are some Notepad++ features:
Syntax Highlighting and Syntax Folding
Print text in colour
User Defined Syntax Highlighting
Edit several documents at the same time
Synchronised scrolling between two documents
Regular Expression Search/Replace supported
Full Drag 'N' Drop support
Zoom in and zoom out
Place bookmarks in the text
Macro recording and playback
For more details, check out the Notepad++ homepage.
If you ever need to do any programming or scripting, Notepad++ will make your life a lot easier.