File Transfer Protocoll (FTP) is a method to transfer files online between a server and a client. For web development it’s crucial, since when you create or modify a website, you need to upload its files.
A more secure FTP connection is the SSH File Transfer Protocol (SFTP), where the username, password and content is encrypted.
You need 3 things to connect to an FTP server. A server adress (domain or IP address), username and password. Besides, there are also anonymus FTPs, where you can log in without password, using only an email address. It’s possible to communicate with an FTP server via command line, but a more easy approach is to use an FTP client, for example the free FileZilla. It’s similar using a Windows Explorer or a Finder. Browsers also support FTP connections.
If you want to start an FTP server on your machine, here are two free solution: