The Present Continuous Tense expresses an activity that is in progress at the moment of speaking. It began in the recent past, is continuing at present, and will probably end at some point in the future.

1. John is sleeping right now.
2. I need an umbrella because it is raining.
3. John and Mary are talking on the phone.

Often the activity is of a general nature: something generally in progress this week, this month, this year.

1. I am taking five courses this semester.
2. John is trying to improve his work habits.
3. She is writing another book this year.

Note: for no. (3), the sentence means that writing a book is a general activity she is engaged in at present, but it does not mean that at the moment of speaking she is sitting at her desk with pen in hand.

When someone uses the present continuous, they are thinking about something that is unfinished or incomplete.

The present continuous is used:

• to describe an action that is going on at this moment e.g. You are using the Internet. You are studying English grammar.
• to describe an action that is going on during this period of time or a trend, e.g.
  Are you still working for the same company? More and more people are becoming vegetarian.
• to describe an action or event in the future, which has already been planned or prepared (See also 'Ways of expressing the future) e.g. We're going on holiday tomorrow. I'm meeting my boyfriend tonight. Are they visiting you next winter?
• to describe a temporary event or situation, e.g. He usually plays the drums, but he's playing bass guitar tonight. The weather forecast was good, but it's raining at the moment.
• with 'always, forever, constantly', to describe and emphasise a continuing series of repeated actions, e.g. Harry and Sally are always arguing! You're forever complaining about your mother-in-law!

BE CAREFUL! Some verbs are not used in the continuous form - see this part.

How do we use the Present Continuous Tense?

We use the present continuous tense to talk about:

• action happening now
• action in the future

Present continuous tense for action happening now

a) for action happening exactly now

I am eating my lunch.
past	present	future
	The action is happening now.

b) for action happening around now

The action may not be happening exactly now, but it is happening just before and just after now, and it is not permanent or habitual.

John is going out with Mary.
past	present	future
	The action is happening around now.

Look at these examples:

• Muriel is learning to drive.
• I am living with my sister until I find an apartment.

Present continuous tense for the future

We can also use the present continuous tense to talk about the future - if we add a future word!! We must add (or understand from the context) a future word. "Future words" include, for example, tomorrow, next year, in June, at Christmas etc. We only use the present continuous tense to talk about the future when we have planned to do something before we speak. We have already made a decision and a plan before speaking.

I am taking my exam next month.
past	present	future
!!!
	A firm plan or programme exists now.	The action is in the future.

Look at these examples:

• We're eating in a restaurant tonight. We've already booked the table..
• They can play tennis with you tomorrow. They're not working.
• When are you starting your new job?

In these examples, we have a firm plan or programme before speaking. The decision and plan were made before speaking.

Sources:

http://www.englishclub.com/

http://www.edufind.com/