Forms are the foundation but no two people do a form the same way. It's all in in terpretation. Forms most often have a theme to them. In my style of Kung Fu, the form Lao Ying tells of all the pressure points on the wood chi channel in the body. I have seen Karate forms that teach how to defend from rear attac ks and Tae Kwon Do forms that show how to fight against someone on horseb ack.
Forms can also show what time of the day to use certain techniques.
Som e Japanese based forms start by looking up to the sun and spreading the a rms halfway. This can tell you to use the moves only till noon. Forms give us all this. Forms can even show you the defense for a technique right in the form. The Kung Fu style of Choy Li Fut has forms that show the counter before t he strike is thrown.