"port" is short for "portal". It allows video feed to transport from one location to the next by particle & molecular transfusion. All you need is a "port" and a type of video connection, such as "HDMI", "VGA", "DVI", or even "S-Video". When assigned, these video connectors to the certain "portal" it will allow your video medium to travel (usually at the speed of light or if lagging by worm-holes, within seconds) to the next dimension. =)
Displayports are handy because of their low profile, which is why it's easy to have multiple display port connectors on a single graphics card (AMD 5870 Eyefinity 6 edition has 6 connections, whereas you wouldn't be able to fit that many DVI or VGA adapters).