An FTP server is a server software or service for file transfer. FTP (File Transfer Protocol) is a network protocol for file transfer between computers. The FTP server allows users to connect to the server through an FTP client to perform operations such as uploading, downloading, deleting, and renaming files.

The FTP server usually provides the following functions:

File storage and management:

The FTP server provides a file storage function, which can save files on the server and manage files, including operations such as creating folders, moving files, and deleting files.

User authentication:

The FTP server supports user authentication. Users need to provide the correct user name and password to connect to the server and access files.

file transfer:

Through the FTP client software, users can use the FTP protocol to establish a connection with the FTP server, and then upload and download files. Users can upload files from their local computer to the server, or download files from the server to their local computer.

File permission control:

The FTP server can set different permissions on files and folders to control users' access to files. Read, write, and execute permissions can be set, as well as access restrictions for specific users or groups of users.

Using an FTP server can facilitate file transfer and sharing between computers. It is very useful in many situations, such as uploading, downloading and backup of website files, file sharing in team collaboration, file management of remote servers, etc. However, it should be noted that since the FTP protocol uses clear text transmission, the transmitted data may be eavesdropped or tampered with, so in the case of high security requirements, you can consider using FTP over SSL/TLS (FTPS) or SSH File Transfer Protocol (SFTP) and other encrypted FTP transmission methods.