The number of advertisement spaces for sale on a web site at a given time.

An online commentary or diary often written by individuals about hobbies or areas of specialist interest. Blogs commonly allow comments below entries and are published in reverse chronological order. Also known as a weblog.

Small text file that is downloaded to your computer when you visit a site. The next time you visit, the site can use the file to remember details such as your login information.

TV signals encoded so only paying subscribers can watch.