The occupied Palestinian territories do no have any control over their external borders. All incoming individuals pass through an Israeli border control. Therefore check Israeli visa information for more info. Normal Israeli tourist visas are valid for three months. They may be delivered for a shorter period (and sometimes not granted at all) if you say that you are going to the territories, if you come from Egypt or the Aqaba-Eilat crossing with Jordan, if you are from Palestinian or Arab origin, if you are suspected of ties with certain groups or of a link with some of the pro-Palestinian NGO's (e.g. the ISM - International Solidarity Movement). Expect very heavy (but normally very polite) security control.|
Within the occupied territories, different cases apply. East-Jerusalem and the Syrian Golan heights have been annexed by Israel (annexation not recognised by the international community), they are thus freely accessible, most of the time no checkpoints will block you on your way. To enter the Westbank and move within it, you will often be confronted with checkpoints where your passport will be controled. In most cases you will get through. However sometimes you may be told that an area is off-limits. This is the case (August 2005) with e.g. Nablus. Places like these are more accessible if you are with public transport than when you are with a rental car, as you have to walk through the checkpoints when you're with a bus, and when you walk into towns you rarely have an ID check (whereas with a car very often). When you walk out, you can just say that you did not know the area was off-limits...
To enter Gaza, one needs a special permit from the Israeli authorities. Currently (August 2006), this permit is only given to persons that can demonstrate a proper reason to go there (foreign aid workers, journalists, ...). The permit has to be asked for through your consulate in the occupied territories or your embassy in Tel Aviv, Israel. It may be that your consulate or embassy wants to enquire for it only if you will be part of a convoy with security personnel. So basically, you will not go to Gaza as a foreigner... For what it is worth, foresee at least five days for the procedure. Only one crossing into Gaza available from Israel: the Erez crossing. The border between Gaza and Egypt opens and closes frequently, access again for foreign aid workers, diplomats, and journalists.
If you have received a separate visa paper when arriving in Israel/Palestine, do NOT lose this precious document. As a side remark, if you intend to travel to countries as Lebanon or Syria with the same passport, you can ask not to have your passport stamped (then you will automatically receive the paper), as you cannot enter the latter countries with any proof of a visit to Israel or Israeli controlled territory. However this may also prolong the questioning procedure with Israeli security personnel.
Information as of August 2006: several persons have been denied entry at Ben Gurion airport (Tel Aviv) because they had Lebanese and or Syrian stamps in their passport.