In computing, "redo" is a function that restores any actions that were previously undone using an "undo" function. It is used to reverse the effects of an undo function and restore the previous state of a document or application. For example, if you typed a word and then deleted it using an undo, the redo function restores the word you deleted.

The redo function is usually accessed through a keyboard shortcut, such as Ctrl+Y or Command+Y on a PC. In Microsoft Word, PowerPoint, and Excel, the redo function can also be accessed by pressing Ctrl+Y or F4.

It is important to note that the redo function can only be used to restore actions that were previously undone using an undo function. Additionally, the order in which actions are redone is the same as the order in which they occurred. Some applications, such as Microsoft Word, include a special toolbar button for the redo function.

Overall, the redo function is a useful tool for reversing the effects of an undo function and restoring the previous state of a document or application.