A CBT file is a Comic Book Tar Archive. It's essentially a TAR archive (a type of compressed file) that contains a series of image files, typically in JPEG, PNG, or GIF format. These images represent the pages of a comic book or graphic novel. The CBT format is designed for easy storage and distribution of digital comics. The images within the archive are usually ordered sequentially to represent the correct reading order of the comic. Comic book reader software can open and display CBT files, allowing users to easily browse through the pages of the comic. The TAR format provides a way to bundle multiple files into a single archive, making it easier to manage and share the comic book content. While compression is often applied to the TAR archive, it's not always the case, and the primary purpose is to create a single, easily manageable file.