MS Excel provides convenient ways of storing and managing small or large amounts of data. Workbooks are widely used to maintain the datasets, analyze the data, perform activities related to finance or human resources, and etc. With the advancement in technology, the ways of getting unauthorized access to data have also been increased. Therefore, MS Excel lets you protect the workbooks using the password. In this article, you will learn how to automate the spreadsheet protection features and protect or unprotect Excel files programmatically using C#.