Here are a few various useful resources:

Microsoft Docs – Documentation on all things Microsoft, should contain almost all the articles from the old MSDN TechNet as well.

Stack Exchange – The root site for various excelent resources like Stack Overflow and Server Fault.

RegExr – Excellent site for creating and testing Regular Expressions (RegEx) strings.

SS64 – References for common scripting languages (across OS-es) and reference for database commands.

My GitHub profile