Same idea as Word — a native format for editing, and other formats for sharing a fixed copy or moving data elsewhere.
| Format | Use it for |
|---|---|
| .xlsx | Excel's own format — keeps formulas and formatting |
| A fixed copy that looks the same everywhere — formulas become plain text | |
| CSV | Plain data only, no formatting or formulas — opens in almost any spreadsheet program, including LibreOffice Calc and Google Sheets |
The universal spreadsheet format
CSV is worth remembering — it's the one format every spreadsheet program, free or paid, can open without any conversion.
File → Info → Protect Workbook can require a password to open a file, or mark it read-only to discourage accidental edits — worth using before sending a spreadsheet to a large group when the numbers shouldn't change.