FTP (File Transfer Protocol) is a standard network protocol used for transferring files between a client and a server over a computer network, typically the internet. It provides a simple and efficient way to upload, download, and manage files on a remote server.

FTP operates on a client-server model, where the client initiates a connection to the server using FTP client software. The FTP client can be a dedicated program or a web browser with FTP capabilities. The server runs FTP server software, which listens for incoming connections and handles file transfer requests.

Here's a step-by-step overview of how an FTP connection works:

1. Authentication: The client establishes a connection with the FTP server by providing a username and password (or sometimes anonymous access is allowed).

2. Commands: Once the connection is established, the client sends commands to the server to perform various operations such as listing files and directories, uploading files, downloading files, creating directories, renaming files, and deleting files.

3. Data Transfer: FTP supports two modes of data transfer: active mode and passive mode. In active mode, the server initiates a connection back to the client for data transfer. In passive mode, the client establishes a secondary connection to the server for data transfer. The actual file data or directory listings are transferred over these data connections.

4. Directory Navigation: The client can navigate the remote server's directory structure using commands like "cd" to change directories and "ls" to list directory contents.

5. File Transfer: The client can upload files to the server using the "put" command and download files from the server using the "get" command. Binary and ASCII modes are available for transferring different types of files.

It's important to note that FTP does not provide encryption for data transmission, which means the files and login credentials are sent in plain text. This lack of security makes FTP vulnerable to eavesdropping and data interception. To address this issue, FTP can be combined with additional protocols like FTPS (FTP over SSL/TLS) or SFTP (SSH File Transfer Protocol) to add encryption and enhance security.

Despite its limitations in security, FTP remains a widely used protocol for file transfer, particularly in situations where security is not a primary concern or when FTP is used internally within a trusted network.