FTP (File Transfer Protocol) is one of the oldest and still most common ways to move files from your own computer onto a server — the literal mechanism behind "uploading your website."
An FTP client — a piece of software on your computer — connects to your server using credentials your host gives you (a hostname, a username, a password, sometimes a port number), and presents two file listings side by side: your local computer's files and the server's files. Dragging a file from one side to the other uploads or downloads it.
Plain FTP sends your username, password, and every file completely unencrypted — anyone intercepting the connection on the network in between can read it all, credentials included. SFTP (SSH File Transfer Protocol — related to SSH, covered in its own lesson shortly) does the same job over an encrypted connection.
Prefer SFTP over plain FTP
Use SFTP, not plain FTP, whenever your host offers it — which is nearly always, today. Sending a server password over plain, unencrypted FTP on an untrusted network is a genuine, avoidable security risk, not a theoretical one.
public_html or www, the folder your host actually serves to visitors.Every file destined to be visible on your site has to actually be inside the server's designated web folder — usually public_html. Files uploaded elsewhere on the server exist, but nothing on the internet can reach them. This single detail causes a large share of "I uploaded it but nothing changed" confusion.
FTP/SFTP is the standard way to deploy to shared hosting and many control-panel-based hosts specifically, since that is what those platforms are built to expect. It is not how cloud and managed platforms typically work — those generally use Git-based deployment instead, covered in its own lesson later in this part.