If you ever want to travel to the Philippines, you must have a passport valid for at least six months within your period of stay. Visitors must have return or onward tickets and documents necessary for further travel.

Most international tourist are covered by the 3-Week Tourist Visa. If you want to stay longer, you can apply for a Visa-Extension, but i think they have an additional fee for that.

If for any reasons you have stayed the length of your stay, whether you're having troubles getting a flight home or just enjoying too much, there is also a 1000 peso / month penalty.

I recommend that you go to your respective country’s consulate office or embassy to check other entry requirements as well as gather more information like Travel Warnings.