A workbook is an electronic spreadsheet file that contains one or more worksheets. Workbooks are the primary file format used for saving data in spreadsheet software.
Workbooks are a container for worksheets, individual documents in which data is entered and calculations are performed. A worksheet is a grid, somewhat like a chart, that contains individual entries called cells. Workbooks can be thought of as folders that can hold several related worksheets for easy access. Although workbooks and spreadsheets are often conflated, the term "spreadsheet" is properly applied to the software as a whole, not to the documents or containers it creates.