Li-on batteries

Hello all,

I have a question about using Li-on batteries in my project. It's basically this, what is really in the larger Li-on packs? Is for example a pack that produces 6,600 MaH and 3.7V - 5V just a bunch of single batteries that have been wired together to form the stronger pack?

Can anybody provide some kind of guidance on how to wire them if this is so?

Forgive my newbieness, thanks for all help.

You should never parallel li ion batteries, just get the cell capacity you want. also great care has to be taken not overcharge or overdischarge the cells, this will damage the cells and can also be a potential fire hazard.
Li ion cells are a advanced technology with high performance but it has its drawbacks. One is that the cell voltage varies a lot, from 4,2 V down to 3V so they almost always have to have a step up regulator to provide a constant 5V voltage