Practically speaking, travelers to Tibet must officially be part of a group tour with a guide. Sometimes this means a couple books a tour package through an agent and sometimes this means several travelers hang out in Chengdu (see Getting There) waiting for enough people to make a group and then traveling on to Lhasa. In any case, this translates into a bit of hassle and extra money spent by the traveler, but once in Tibet, it is fairly easy to make arrangements to see the sights you'd like.
If you want to get off the beaten tourist group path and see some of the more remote areas of Tibet, you will have to obtain a PSB Permit or Alien's Travel Permit. This gives you greater access to different areas of Tibet. These are also organized through a tour agency.
Foreign government officials, diplomats and journalists have to organize their travel permits through a different channel. If you fall into this category, you should have your office work with the Foreign Affairs Office of Tibet Government to obtain the correct permits.
