FTP : File Transfer Protocol

Back in the "Stone-Age" of computers/networking (which is just 25 year ago!), users were only able to "dream" of "Online Data Exchange between Systems" (something we take today for granted).
But in those days, each computer manufacturer use a proprietary operating system and proprietary communication protocols ("boxing" in their clients, ensuring they could only purchase systems expansions from them to be able to connect any additional equipment).

That was a huge problem for the DoD (US Department of Defense) and its DARPA (Defense Advanced Research Project Agency), because they could not exchange data between the different research locations.
They solved that problem (I think in 1972) by requiring support for TCP/IP on all computers, which the DoD and their contractors were to purchase in future.
And since the DoD paid high prices (very high prices ! ) for their equipment, the computer industry had to agree to implement TCP/IP and its component:
FTP: File Transfer Protocol
It does EXACTLY that: transfer files (ok, it includes also the possibility to list directories, change directories and a few other commands, but these were mainly used to locale the file to be transferred) and it does this REGARDLESS of the operating systems of the systems:

It does not matter anymore, if the Server modules is not compatible with the Client-module, as long as both systems have TCP/IP-protocol installed and the server has an FTP-Server running.

FTP allows to transfer files, it does NOT allow direct file-manipulation (like connection to a database-file to add a few records).
If you like to modify a file, you need:
- use FTP to transfer the file to your local system
- modify the file
- use FTP to transfer the file back to its original system.

When to use FTP:
- in case that the systems do not have matching Client-to-Server software
- Wide-Area-Networks, which are usual slow and need to be efficient

The growth of the Internet has made FTP an important protocol, because many companies make updates/patches of their software on FTP-servers for download.
But you can create your own "Intranet" FTP-server, using the
Windows 95 Microsoft "Personal Web Server"

Most Internet FTP-servers allow "Anonymous" FTP, i.e. when you are prompted for the Username, enter either "ftp" or "anonymous".
As password, you will then be prompted to enter your e-mail address.

There a different methods to operate an FTP-Client:
FTP: Command-Line Operation
FTP: Internet Browsers
FTP: GUI-Clients (Ipswitch WS-FTP)