Excel’s unwritten rule
Over the years, I’ve observed an unwritten rule that I find many users unwittingly break: the first row of any list should be a single row of unique titles—or Headers in Excel vernacular. This applies to every list that you create in Excel, no matter if you’re using the Table feature or not. Headers are so crucial that the Table feature adds placeholder Headers when needed. Both Tables and PivotTables require that each Header be unique and will append numbers to duplicate Headers to enforce compliance.
Tip
An addendum to the preceding rule is that lists should not have any blank rows or columns. Most Excel features act on the Current Region, which is the contiguous block of non-blank cells surrounding the active cell. Blank rows and columns truncate the Current Region, and they require you to manually select the entire list before sorting or filtering instead of being able to choose a cell within the list and then sort or filter...
