FTP is File Transfer Protocol. This is the main protocol for transferring files. So you can receive or send file extensions like .jpg, .avi, .exe, .dat, and .html. But does this mean when I'm looking at an .html it actually came to me through FTP. No, it's the final outcome that determines what protocol your using. FTP just copies the file from computer to computer. That's it; it doesn't execute or rename it. That's what software does. FTP just copies or deletes the file in question. The problem is that this protocol is blind and needs the user or software to indicate what to download. The good thing about this protocol is that it can resume, or finish a download of a file based off the last packet of a file as long as the software supports such a thing.
FAQ answers attributed to Raymond E. Feist are copyright by Raymond E. Feist.
It should also be born in mind that the answer given was only applicable on the date written, and to a specific question. You may find further, similar questions, in the FAQ.