Present Progressive (Continuous)

We use the present continuous for a present action over a period of time, something that we are in the middle of now. 

The action has started but it hasn't finished yet.

What are you reading? 'Macbeth'.

~ It's raining now, look.

Hurry up. Your friends are waiting for you.

I'm just ironing this shirt.

Some typical time expressions with the present continuous are now, at the moment, at present, just, already and still.

We need not be doing the action at the moment of speaking.

I'm reading an interesting book. I can't remember what it's called.

We'd better get home. We're decorating the living-room at the moment.