What is FTP?

FTP stands for "File Transfer Protocol". It is a standard way to exchanging files over the WWW. The simplest way to think of it is that is a souped-up "Copy" command. In UNIX or LINUX, you can copy a file from here to there with "cp", and in Windows, by using Windows Explorer. If you want to copy a file from one computer to another, at some distance, you need FTP.

The most common use of FTP is for downloading files from computers which are set up as FTP servers or FTP sites. There may be multiple FTP sites which contain the same files; these are sometimes called "mirror sites".

FTP is also used to upload files, that is, to copy them from the user's computer to a server. For instance, if you have a web site, you will need to upload files to the web server.

Sometimes we use FTP without realizing it. If you visit a web site and click on something that says "Download ...", a box may pop up asking what you want to do with with file: save it or open it, etc. This is implicitly using FTP. Note: It can be dangerous to open some random file obtained in this way. Use a virus-checker.

How do I download files?

To download files from an FTP site, you can use your browser:

• You need the URL of the FTP site. This will begin with "ftp://" instead of "http://". You typically obtain this as a link from somewhere else.
  
• In some cases, you will need log in with a User ID and a Password. You may need to apply for these or get permission from someone. Some FTP sites are open to everyone but will still want you to log in, in which case the User ID may be "anonymous" and the Password may be your e-mail address (or it may be "guest" and "guest").
  
• In many cases, the files are free to anyone and the site may not even ask who you are.

Of course, some files can be downloaded, but only for a fee. This is common way to sell software nowadays. The FTP site may ask you for payment.

How do I upload files?

Uploading files is more complicated, and your browser probably is not the right tool. You will need FTP software, specifically an FTP client. There are lots of FTP client programs, and you can download some of them (free).

If you are using Windows, you can use the built-in Windows FTP. Read about it in the Windows help files. It is a command-line application. To use it, pick "Start" followed by "Accessories" and "Run" and then type in "cmd". You will then have a DOS window and a prompt. (Some Windows FTP programs are simply "wrappers" around the built-in Windows FTP program and do their work by using it.)

If you are using a Macintosh, you could use "Classic FTP", which is free.

For Windows or Macintosh (or various other platforms), you could use FileZilla, which is also free.