FTP web services.

FTP, or File Transfer Protocol, is a standard network protocol used for the transfer of computer files between a client and server on a computer network. Here's a step-by-step guide on how FTP web services work:

1. Establishing Connection: The client (which could be a computer or a smartphone) connects to the server using an FTP client. The FTP client is a software that allows you to upload, download, and manage files on the server. Examples of FTP clients include FileZilla, WinSCP, and Cyberduck.

2. Authentication: After the connection is established, the client needs to be authenticated before it can access the files on the server. This is usually done by entering a username and password. However, some servers allow anonymous logins where you don't need a username and password.

3. Data Transfer: Once authenticated, the client can now perform various operations such as uploading files to the server, downloading files from the server, renaming or deleting files on the server, etc. The data transfer can happen in either ASCII mode (for text files) or Binary mode (for binary files like images, audio files, etc.).

4. Closing Connection: After the client is done with its operations, it can send a command to the server to close the connection. The server will then terminate the connection.

FTP web services are commonly used in website development where developers need to upload their website files to the server so that they can be accessed over the internet. They are also used in data sharing where large files that can't be sent via email can be uploaded to an FTP server and then downloaded by the recipient.