An IFF file is a universal file format created by Electronic Arts. It may contain image, text, or audio data and is used for interchanging different types of data across applications and platforms. IFF files are supported by many programs and are used as the basis for several other file formats, including AIFF.

IFF files are comprised of sections of data called "chunks," which are defined by four-letter IDs. There are three main chunk types, each of which may contain text, numerical data, or raw data: FORM: specifies the format of the file LIST: includes the properties of the file CAT: contains the rest of the data The IFF format is also known as "EA IFF 1985" since Electronic Arts designed the file format in 1985. NOTE: IFF files used by The Sims and The Sims Online can be edited using IFF Snooper for the Mac platform or IFF Pencil for Windows.