Israel controls all the borders of the Palestinian territories, as well as the actual territories. Depending on where you are from you might need to apply for a visa, or you will automatically get a 3 months tourist visa on arrival in the airport (this goes for citizens of EU member states and the US). For more information on the regulations applying to your country of origin, contact the Israeli embassy in your home country.
If you wish to travel to certain middle eastern countries and then return, your visa lasts only 30 days when entering Israeli borders again. On arrival, you receive a small piece of paper with a code and your passport photo printed on it – this is your visa. You are to keep this and your passport on you at all times when travelling around.
To enter Israel your passport should be valid for a minimum of six months.
If you have stamps from Arabic countries in your passport you can expect increased check on both arrival and departure.
Due to the often long security check in the airport, you need to be in the airport 3 hours before departure.