This page is full of commonly used web terms and acronyms:
Domain
A domain name typically refers to a human readable name for a computer connected to the internet (there many exceptions to this definition). riseup.net is a domain name, www.riseup.net is a different domain name. Using a DNS, your computer coverts the domain name to a numerical internet address that can be used to find the web server.
DNS
Domain Name Server. To find a particular web-site, your computer first connects to a Domain Name Server to find the address of the web-site. When you register a domain, you need to specify what DNS will hold this information for your domain. Some domain registrars will 'host' the DNS for you, but most will not. Typically, you will need riseup.net to host your domain.
Host
On the internet, the term 'host' is used in many ways: it can mean both your computer at home (the local host or client), it can also mean a remote computer where the web-site is stored (the remote host or server). When a web-site is stored on a server, it is said to be 'hosted' by that server.
FTP
File Transfer Protocol. FTP is the most common way to upload files from your computer to a web server. riseup.net no longers supports FTP, because it is too insecure.
SFTP
Secure File Transfer Protocol. You can think of SFTP as FTP over an encrypted connection. (although it is actually ftp-like commands over ssh).
SCP
Secure CoPy: A method of copying files over SSH. Some clients support SCP but not SFTP. With riseup.net, you can use either SCP or SFTP.
SSH
Secure SHell: A method for logging into a remote machine over an encrypted connection. You get a shell prompt (command line interface( once logged in.
URL
Abbreviation of Uniform Resource Locater, the global address of documents and other resources on the World Wide Web. The first part of the address indicates what protocol to use, and the second part specifies the IP address or the domain name where the resource is located.