Format refers to the way in which something is arranged or presented.
In computing, format means:
1. The structure of a file (e.g. MP3, PDF, DOCX)
2. To prepare a storage device for use (e.g. formatting a hard drive)
In everyday usage, format can mean:
1. The layout of a document (e.g. report format)
2. The style of a TV show (e.g. talk show format)
3. The arrangement of data (e.g. date format)