Each of the main areas also have an AccessKey assigned to them. This means that you can use the keyboard to jump to any main area from anywhere else in the site.
AccessKeys work slightly differently on Macs and PCs. Below is a list of the main areas of the site, and the keyboard commands that will jump to them.
alt + 1 > rtn
'alt + 1 > rtn' means that you must hold the alt key and the 1 key at the same time, then press the Return key.
'ctrl + 1' means that you must hold the ctrl key and the 1 key at the same time.