Protect Sheet is one of the most useful features in Excel and one of the most misunderstood. It is brilliant at its real job: stopping a shared file from being quietly wrecked by the tenth person who opens it. It is useless at the job people often give it: keeping the data secret. This guide is clear about both halves.
You will find Protect Sheet on the Review tab, and it does ask for a password, which is where the confusion begins. A password box feels like security. But where the video in this series sets a password that encrypts the file, sheet protection simply records a rule inside the file: Excel, refuse edits here. This page shows how to use that rule properly, and how to recognise the moment you actually needed the other lock.
Set on a sheet where some cells are locked, which is the default state of every cell until you unlock it, protection makes Excel refuse changes: no typing over a formula, no pasting into a total row, no deleting the columns your format depends on, within the limits you tick in the dialog. For a billing format, a stock register or a shared data-entry sheet, this prevents the most common office accident there is: a good file slowly corrupted by innocent edits nobody noticed.
Used this way, it is excellent. Pair it with unlocked input cells, covered in the third section, and the sheet becomes a form that staff can fill but cannot break.
It does not stop reading. Anyone who can open the file can see every value and every formula, copy whole ranges out into another file, and print the sheet. It does not encrypt anything: the workbook's contents remain ordinary, readable data inside the file.
And the protection itself is only a stored setting inside that file. On your own file, a forgotten sheet password is removable, because the lock is a flag Excel checks, not a mathematical barrier. That is good news when you lock yourself out of your own format, and it is exactly why a determined person cannot be kept out by it either. Both facts come from the same design: this is a courtesy lock.
Most failed sheet protection comes from protecting everything, so staff cannot type anywhere and someone unprotects the sheet and never puts it back. Do it in this order instead:
Record the password where you record the file's other passwords. You will need it the day the format itself has to change.
Next to Protect Sheet, the Review tab offers Protect Workbook, which guards the structure: sheets cannot be added, deleted, renamed, moved or hidden. It answers a different accident, the missing sheet, not broken cells.
Grade it exactly the same way. It is a useful rule for a finished workbook whose layout other sheets and formulas depend on, and it is no kind of secrecy. The file opens, everything in it can be read, and the protection is again just a setting stored in the file.
If the real worry is that someone will see the data, salaries, prices, marks, medical notes, then no Review tab option will help you, and reaching for one gives false comfort. The correct tool is the file-open password: open the file, press F12, Tools, General Options, Password to open, as the video in this series shows. That encrypts the workbook, and the file then shows nothing at all until the password is given. Use sheet protection to guard the working file inside the office, and the open password to guard the file anywhere it travels. The two are partners, not substitutes.
The video sets this password on a real Excel file in about a minute, including the confirmation step and the save.
Watch Full VideoNo. Protection stops formulas from being changed, not from being seen. Anyone who opens the file can click a cell and read its formula in the formula bar. There is a Hidden option in cell protection that hides formulas from the bar, but the file is still unencrypted, so it is a courtesy measure, not secrecy. For real secrecy, encrypt the file with a Password to open.
No, and that fact tells you everything about this lock. Sheet protection is a setting stored inside your file, not encryption, so on a file that is yours it can be dealt with and removed. This is completely different from a forgotten Password to open, where the data really is locked away.
Usually yes. It means the cells staff legitimately need are locked. Unlock the input cells first (Format Cells, Protection, untick Locked), then protect the sheet. If people can do their whole job without unprotecting, they stop asking, and the protection survives.