1. In general, overwrite is a term used to describe when new information replaces old information or data.
2. One of two typing settings on a keyboard, overwrite mode allows new input to replace existing characters. The Insert keyboard key is commonly used to toggle this mode, enabling or disabling it. If you've overwritten any text it can be undone by using undo in most programs.
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.