SciTE is a powerful programmer's editor and Notepad replacement based on the popular open-source Scintilla (a component used within many other editing tools).
You don't need to be a developer to use the program. It looks much like Notepad, so at a minimum you can just launch it, type some text and save the file, using all the keyboard shortcuts you know already.
It won't take long to notice small benefits. Pressing Ctrl+N creates a new tab, for instance, allowing multiple documents to be open at once. And Ctrl+F gives you a persistent search area at the bottom of the screen, where you can instantly mark all search hits as well as zip through them one-by-one.
Start exploring the program and you'll quickly discover more. Regular expression searches, find across files, drag and drop editing (select some lines, drag and drop them somewhere else), case conversion, bookmarking, session management.
There's also plenty of developer-oriented power, including syntax highlighting, brace handling, code folding, and options to compile and run programs, turning it more into a basic IDE.
SciTE isn't the most powerful of programmer's editors, but it's also easier to use than many, and the core editor (Scintilla) is one of the best around. If you're not currently happy with some other Notepad replacement, it's a must-try.
Version 4.4.4 Changelog:
Released 21 July 2020.
End of line annotations implemented. Bug #2141.
Add SCI_BRACEMATCHNEXT API. Feature #1368.
The latex lexer supports lstlisting environment that is similar to verbatim. Feature #1358.
For SciTE on Linux, place liblexilla.so and libscintilla.so in /usr/lib/scite. Bug #2184.
Round SCI_TEXTWIDTH instead of truncating as this may be more accurate when sizing application elements to match text. Feature #1355.
Display DEL control character as visible "DEL" block like other control characters. Feature #1369.
Allow caret width to be up to 20 pixels. Feature #1361.
SciTE on Windows adds create.hidden.console option to stop console window flashing when Lua script calls os.execute or io.popen.
Fix translucent rectangle drawing on Qt. When drawing a translucent selection, there were edge artifacts as the calls used were drawing outlines over fill areas. Make bottom and right borders on INDIC_ROUNDBOX be same intensity as top and left. Replaced some deprecated Qt calls with currently supported calls.
Fix printing on Windows to use correct text size. Bug #2185.
Fix bug on Win32 where calling WM_GETTEXT for more text than in document could return less text than in document.
Fixed a bug in SciTE with Lua stack balance causing failure to find functions after reloading script. Bug #2176.