A ball head is a tripod head where the camera movement is locked with a single lever. The camera is mounted on a post fixed to the ball and when the head is slackened off the ball can move freely in any direction. [Read more…] about Ball head
The main part of a tripod is the three legs, but most also have a centre column that extends upwards still further for extra height. [Read more…] about Centre column
Travel tripods are designed for compactness and light weight so that they can more easily be strapped to bags or even carried inside them. They have a specific design feature, whereby the legs fold upwards around the centre column and the tripod head to minimise their size when folded.
This is the part on the top of the tripod that allows you to move the camera and then lock it in position. You can get ball heads, which allow free movement in all direction but not much precision, or three-way heads which are slower to use but enable you to move the camera in one axis at a time.
Three-legged camera support that doesn’t really need much more explanation, except to say that they vary considerably in cost, size and rigidity, and that some come with tripod heads while others require you to buy them separately.