Japan Rail Pass

The pass includes unlimited, all-year-round and 24/7 travel for 7, 14 or 21 consecutive days (depending on the pass) on train lines operated by Japan Railways (JR) throughout Japan, including the famous bullet train, commonly known as Shinkansen. Besides train travel in JR's rail network, the Japan Rail Pass is valid on:

Local JR buses on a large number of lines
JR Miyajima Ferry in Hiroshima
The Tokyo Monorail connecting Haneda Airport to Hamamatsucho Station
Some lines of Aoimori Railways

The Japan Rail Pass is NOT valid on:
High-speed Nozomi trains. If you use a Nozomi, you must pay a surcharge before boarding the train.
On the Tokyo Metro
On private (non-JR) railway lines such as: Hakone-Tozan, Nankai Koya, Fujikyu, Kitakinki-Tango. Some JR trains do travel over non-JR tracks and Japan Rail Pass holders are required to pay a supplement for this part of the journey (either on board or at the station).

Japan Rail Pass can only be purchased outside Japan.
The Japan Rail Pass can only be ordered up to 90 days in advance. For example, if your order is printed 01 March, it means you can exchange your order in Japan to get a pass at the latest 30 May.
The pass can only be used by foreign tourists and Japanese nationals living outside Japan who meet certain conditions.
Once in Japan, you will need your passport to exchange your voucher for the Japan Rail Pass.
After exchanging your voucher, you will need to start using your pass within 30 days.
The activation date of the pass (which should be within 90 days from the date of issue), can no longer be changed once the pass has been exchanged.
Children under the age of 6 years old can travel for free as long as they travel with a pass holder.
Children between the age of 6 and 11 years old are eligible for children's Japan Rail Pass. From 12 years onwards children will have to travel with an adult Japan Rail Pass.