FTP.

File Transfer Protocol

• The File Transfer Protocol (FTP) is the most widely used protocol to transfer any kind of file over the network. 
• It is also used for downloading the files to computer from other servers.
• FTP works on Client/Server Model where a client requests file from Server and server sends requested resource back to the client.
• FTP uses out-of-band controlling i.e. FTP uses TCP port 20 for exchanging controlling information and the actual data is sent over TCP port 21.
• The client requests the server for a file. When the server receives a request for a file, it opens a TCP connection for the client and transfers the file. After the transfer is complete, the server closes the connection. For a second file, client requests again and the server reopens a new TCP connection.

Connections of FTP:

Control Connection

• The control connection uses very simple rules for data communication. 
• With the help of control connection, we can transfer a line of command or line of response at a time. 
• The control connection is made between the control processes. 
• The control connection remains connected during the entire interactive FTP session.

Data Connection

• The Data Connection uses very complex rules because data types may vary data to data. 
• The data connection is always made between data transfer processes. 
• The data connection opens when a command comes for transferring the files and closes when the file transfer is completed.

Advantages of FTP

Speed

• One of the biggest advantages of FTP is speed. The FTP is one of the fastest way to transfer the files from one computer to another computer at a short time.

Efficient

• It is more efficient because we do not need to complete all the operations to get the entire file.

Security

• To access the FTP server, we need to login with the username and password. 
• Therefore, we can say that FTP is more secure.

Back & forth movement

• FTP allows us to transfer the files back and forth. Suppose you are a manager of the company, you send some information to all the employees, and they all send information back on the same server.