The Gimp is capable of reading and writing a large variety of graphics file formats. With the exception of Gimp's native XCF file type, file handling is done by plug-ins. Thus, it is relatively easy to extend Gimp to new file types when the need arises.

Not all file types are equally good for all purposes. This part of the documentation should help you understand the advantages and disadvantages of each type.

There is no file format, with the exception of Gimp's native XCF format, that is capable of storing all the data in a Gimp image. When you ask to save an image in a format that will not completely represent it, Gimp notifies you of this, tells you what kind of information will be lost, and asks you whether you would like to "export" the image in a form that the file type can handle. Exporting an image does not modify the image itself, so you do not lose anything by doing this.

[Note] Note
When you close an image (possibly by quitting Gimp), you are warned if the image is "dirty"; that is, if it has been changed without subsequently being saved. Saving an image in any file format will cause the image to be considered "not dirty", even if the file format does not represent all of the information from the image.