Hand Seals

Why do we use hand seals?
Hand Seals are used to perform many Ninjutsu, Genjutsu, and other secret arts other than Taijutsu. The exact amount of chakra necessary to perform a technique is manipulated through hand seals. Chakra is controled through the following Hand seals and when put in a certain order a jutsu is performed.

When To Use
By placing certain hand combos, Chakra is controlled through certain gates. When all Chakra is controlled you can release a Jutsu. High skilled Shinobi can use just one hand seal to make a certain jutsu while most Gennie/chunnin will have to use multiple Hand Seals.

I can use just one hand?
Yes, Certain Shinobi are very skillled and only need one hand to make a hand seal. However it means that shinobi has extreme ability in chakra control. This can be used to do Two jutsus at the same time. Let it be known that most Shinobis will never accomplish this ability.