Notepad++ is free and open source, first released in 2003 by Don Ho. It supports several programming languages and features syntax highlighting, syntax folding, PCRE (Perl Compatible Regular Expression) search/replace, auto-completion, multi-document editing, WYSIWYG printing, zoom in and zoom out, bookmarks, macro recording and playback, and more. Notepad++ is basically what would happen if you were to inject Notepad with steroids and forced it to work out.
Naturally, many Mac users sooner or later look for an alternative, and they often stumble upon Notepad++. TextEdit is the default text editor in macOS, and it’s just as barebones as the default text editor in Windows, Notepad.
