Another nice feature is the ability to add a password. Only people who know the password can turn off the protection and make edits. In the same window, you also have the option of turning on certain functionality while keeping others locked. To turn on Protection, go to Tools > Protection. The Protection function locks all cells by default, so nobody can enter or alter any information. If you share spreadsheets with colleagues but don’t want them to change the content, the Protection function in Excel can be helpful.