What is an Excel workbook?
Quick answer
An Excel workbook is a single Excel file, usually saved as .xlsx. It holds one or more worksheets (the tabs along the bottom), and each worksheet is a grid of cells. "Workbook" means the file; "worksheet" or "sheet" means one tab inside it.
Last updated
Updated · By Robert Breen
Why it matters
Mixing up the two words causes real confusion: "send me the sheet" can mean the whole file or one tab. Knowing the difference also helps you organize. Related data goes in one workbook on separate tabs, so formulas can refer from one tab to another, while unrelated work belongs in separate files.
Where the workbook is saved matters as much as what is in it. A workbook in OneDrive or SharePoint can be shared as a link and edited by several people at once; one on a desktop has to be attached, which creates copies.
A worked example
A landscaping company keeps one workbook for 2026 jobs. The first tab, Jobs, lists every job with date, client, crew and price. A second tab, Prices, holds the price list. A third tab, Summary, totals revenue by month with formulas that read from Jobs, so the owner only ever types on the Jobs tab.
When the price of mulch goes up, the office manager changes one cell on the Prices tab. Every quote formula that refers to it updates across the workbook, instead of someone hunting through a dozen separate files.
Often confused with
Workbook vs worksheet
The workbook is the file. A worksheet is one tab in it. A workbook can hold many worksheets.
Workbook vs table
An Excel table is a formatted block of data inside one worksheet. One worksheet can hold several tables, though one per sheet is easiest to manage.
.xlsx vs .csv
An .xlsx workbook keeps formulas, formatting and multiple tabs. A CSV file is plain text with one sheet of values only, which is why exports from other systems often come as CSV.
Tips
- Name tabs for what they hold (Jobs, Prices, Summary), not Sheet1 and Sheet2.
- Keep raw data and summaries on separate tabs.
- Rename a new workbook straight away; "Book 1" is hard to find later.
Related terms
Learn it in a free lesson
- Excel for the Web Tutorial: Your First Budget Spreadsheet (about 15 minutes)
Related in the AI glossary
Sources
Written from these official help pages. Menus change, so if a button has moved, the help page has the current wording.
Frequently asked questions
- How many sheets can an Excel workbook have?
- As many as your computer’s memory allows. In practice, more than 15 to 20 tabs usually means the workbook should be split.
- Can a formula use data from another tab?
- Yes. Refer to the sheet name, for example =Prices!B2, or click the other tab while typing the formula.
- What file type should I save a workbook as?
- Use .xlsx for normal workbooks. Use .xlsm only if it contains macros, and CSV only when another system needs plain values.
All microsoft 365 terms, A to Z · Free microsoft 365 lessons