Question for Artificial neural network (ANN).....

HI,

I want to know about the working or u can say why we go for neural network as we already have lots of uC to do our work??
as i have seen there are feed forward and backward with lot of activation function...
what does they mean in real??
what the use of using different function for activation.

Neural networks have the possibility of doing things that the brain does well, like facial or voice recognition, for which it is difficult to get digital computers to do efficiently. Thus they are trying to develop neural networks for such applications. They don't necessarily work as well as digital computers for the things that digital computers do easily, such as manipulating tabulated data.

OK, can u please explain me about the function used like sigmoid i not getting it real use like working reading is not satisfy my doubt please clear ...!!

Thanks

help needed..