Notepad++ is a great utility for coders in a Windows environment. Essentially Notepad++ is a combination of the simplicity of (the built-in Windows app) Notepad plus a lot more features specific to coders like syntax highlighting and auto-completion, which it picks up on automatically by understanding the file type extension when you save the file. You can also specify the language manually from a really long list if you’d prefer.
Along with those cool little features, this open-source package is still tiny in size and small in memory footprint. It also brings a spell-checker, macros, and tabs to the interface to make it as fully functional as possible. Beyond that, there are many community developed plug-ins and the ability to extend the program on your own with your own plug-ins. One great plugin is the Compare plugin which lets you diff two files. Another, NppFTP allows you to connect to an FTP server and upload your file, which makes working on code or a website very quick and easy.
Notepad++ is just as versatile as notepad.exe in the ability to open just about any file, makes coding easier with syntax highlighting, and is adaptable (with plug-ins and a flexible configuration). The tabbed interface helps keep you organized by allowing you to have all the files of a project open at the same time, and in one window.