Overwrite may refer to any of the following:
1. In general, overwrite is a term used to describe when new information replaces old information or data. For example, in a text editor, if text was highlighted, and you pressed "a" on the keyboard all highlighted text would be replaced with the letter "a."
In most programs, if you've overwritten any text, and you want to get the text back, you can undo the change.
3. When referring to a virus, an overwrite virus is a computer virus that overwrites a file with its own code, helping spread the virus to other files and computers.