Why direct current is not used for transission of electricity through wires?

Two reasons:

1. Alternating current does not loose as much power over long distance.

2. Alternating current can be stepped up or down through Transformers, allowing AC to be transmitted at high voltage (even less current loss) and then it can be stepped back down inside your home.

For short distances and if there is no need to step up or down, DC is fine.