The .EXT extension file can contain various types of data, saved in binary or text format.

.EXT is a general extension, and is short for extension, usually given to attachments sent by e-mail using automated scripts or various programs. Many sample codes of such programs contain a general record of commands for sending attachments in a file with the "filename.ext" name and extension, and if a programmer chooses not to change this name, a user on the other end will get an e-mail with exactly this attachment. Usually a recipient receiving a message with an EXT attachment will not know what it contains and in what format its content is stored, so it is recommended that you contact the sender to determine the appropriate file or program for opening the particular file.