A CGM file is an image saved in a vector graphics format designed to support the needs of many graphics applications. It was originally used for clip art libraries, but newer revisions (based on the ISO/IEC 8632 standard) are now commonly used for CAD drawings.

CGM files are encoded using one of three different methods: Binary encoding - Standard file encoding that enables software programs to read the file quickly and efficiently. Character-based encoding - Produces the smallest possible file size, which saves disk space and allows for faster data transfers. Clear-text encoding - Allows users to read and understand the contents of the file and modify the file using a basic text editor.