File with a .CGM extension contains a vector image encoded with a one of three possible methods compliant with the ISO / IEC 8632 norm. It may be coded into a text format, easily read and understood by a man, enabling change of the image with a text editor, and also a format based on symbols – the most effective one, when it comes to the levels of data compression, making its transfer easier. The third type of coding is the binary format, identified as standard due to the fact, that it is fast to read by the software.

The CGM format was created in order to make it easier to exchange vector images between different applications. It is widely used. Originally it was utilised to operate the clipart libraries, however, the latest versions are often used in professional drawings creation within the CAD software.