Notepad++ is a Scintilla-based source editor (c, c++, java, html, xml, php, javascript etc...) written in C++ with the win32 API (without MFC). 
The aim of Notepad++ is to offer the programmer a better GUI and to offer the general user a better customisable Notepad.

Main features of Notepad++ : 
1. To colourise the user defined words. 
2. To print the source code in color (or whatever you want) : if you have a color printer(WYSIWYG).
3. The multi-view feature, that allows user to edit the different document in the same time, and even to edit the same document synchronizely in 2 different views. 
4. Support the fully drag and drop : not only you can drop the file from explorer to open it, but also you can drag and drop a document from a view to another.
5. And much more...