Formulas
VLOOKUP vs. XLOOKUP: Stop Fighting Your Lookups
XLOOKUP fixes almost everything that made VLOOKUP painful. Here's how to switch.
Analysis
Pivot Tables for Beginners: Summarize 10,000 Rows in 60 Seconds
The single highest-leverage Excel skill, explained without the jargon.
Troubleshooting
5 Formula Mistakes That Quietly Break Your Spreadsheets
These errors don't always show #ERROR. They just give wrong numbers.