FTP, or File Transfer Protocol, is a standard network protocol used to transfer files between a client and a server on a computer network, such as the internet. It operates on a client-server architecture, where the client initiates a connection to the server to perform file transfers.

Key features of FTP include:

1. Client-Server Model:
   • FTP follows a client-server model. The client is the user’s device, such as a computer or FTP client software, and the server is the remote machine that hosts the files.
2. Two Channels:
   • FTP uses two channels for communication: the command channel and the data channel. The command channel is used for sending commands from the client to the server, and the data channel is used for transferring files.
3. Commands:
   • FTP clients send commands to the server to perform operations such as uploading (put), downloading (get), deleting (delete), renaming (rename), listing directory contents (ls), and navigating directories (cd).
4. Authentication:
   • Users typically need to authenticate themselves by providing a username and password to access the FTP server. Some FTP servers also support anonymous logins.
5. Modes:
   • FTP supports two modes for transferring data: active mode and passive mode. In active mode, the client opens a random port for data transfer, while in passive mode, the server opens a port.
6. Port Numbers:
   • FTP uses well-known port numbers for communication. Port 21 is commonly used for the command channel, and additional ports are used for data transfer, depending on the mode (20 for active mode and a range of ports in passive mode).
7. Security:
   • Traditional FTP transmits data, including usernames and passwords, in plain text, making it susceptible to interception. For enhanced security, protocols like FTPS (FTP Secure) or SFTP (SSH File Transfer Protocol) are used, adding encryption to the data transfer process.
8. Use Cases:
   • FTP is widely used for various purposes, including uploading files to a website, sharing files between computers, updating software repositories, and facilitating large-scale data transfers.
9. FTP Clients:
   • Users interact with FTP using FTP client software, which can be command-line-based or graphical. Popular graphical FTP clients include FileZilla, WinSCP, and Cyberduck.

FTP has been a fundamental protocol for file transfer on the internet for many years, although its use has declined in favor of more secure alternatives like SFTP and HTTPS (HTTP Secure). Despite its limitations in security, FTP remains a simple and widely supported protocol for various file transfer needs.