The present continuous is a verb, an action that we are doing at the time of speaking.We use it to talk about actions we are doing now.
The time markers we use for the present continuous are always, usually, sometimes, rarely and never.
The structure of the present continuous is the auxiliary verb (to be)+verb-ing.
Some examples are:
I'm sitting on a train, looking out at the rain. Now I'm working. I'm going to McDonalds today.