What is Notepad++?
Notepad++ [notepad-plus-plus.org], also called NPP, is a source code editor available for Windows.
Although its name is similar, Notepad++ isn't the same thing as Notepad, the text editor made by Microsoft that comes installed on Windows by default. Notepad is a simple text editor and although you can program in Notepad anything you can program in Notepad++, it lacks many features for source code editing that Notepad++ has, including syntax highlighting, regex search and replace, and visible whitespace. Even as a text editor, Notepad++ is better than Notepad, as Notepad++ supports more text encodings than Notepad supports.
Many Windows developers use Notepad++. I use it as well. It's great when you're working with a single file or a piece of text you copied from the Internet. However, if you're working with complex multi-file projects, I recommend using Visual Studio Code or a specialized IDE.