It refers to a set of standards so that no matter what the operating systems of a computer and server, files can be transmitted from one to another. 

It works in a way that is similar to the more familiar HTTP that is typed in at the beginning of a web page. The HTTP:// alerts the computer that you are connecting to that you want to view the contents of a file, like a web page or a movie. The HTTP also allows for limited downloads, such as when you click on a link and save a program to your computer.

The major difference is that HTTP can't be used to send files, only receive them. FTP permits you to both send and receive, and transfers files rather than viewing them. Because the server doesn't have to do any interpreting of the page and organizes the data differently, it tends to be faster and more efficient, which is why many sites that offer downloads have an FTP option.

There are two modes for sending files, ASCII and Binary. ASCII is a very specific way of encoding characters used for writing, such as letters, numbers, and punctuation. Each character is represented by a unique number (see a chart of the characters and their numeric value). ASCII is used for sending plain text. What types of files do I send using ASCII?

The other mode is binary. Binary refers to the way data is stored on a machine, meaning that the entire file is stored as 1's or 0's. Binary sends the file along with the basic information as to what type of file it is and how it is stored. What types of files do I send using binary?