(TIFF) A file format used for still-image bitmaps, stored in tagged fields. Application programs can use the tags to accept or ignore fields, depending on their capabilities. While TIFF was designed to be extensible, it lacked a core of useful functionality, so that most useful functions (e.g. lossless 24-bit colour) requires nonstandard, often redundant, extensions. The incompatibility of extensions has led some to expand "TIFF" as "Thousands of Incompatible File Formats". Compare GIF, PNG, JPEG.