First on the list is Notepad++. This is not your Father's MS Notepad. :hah: Remember, NEVER use MS Notepad or MS Word/Write for file editing!!!
Notepad++ is very useful for editing PHP, HTML, ASP, etc. files. Pretty much any file that you use on the web except for images can be edited including mySQL files. It is great for beginners and advanced users.
https://notepad-plus-plus.org/ (https://notepad-plus-plus.org/)
There are also a number of plugins that you can read about and add from here:
http://docs.notepad-plus-plus.org/index.php?title=Plugin_Central
+1 for Notepad++
It is my first choice for editing most any kind of web file.