Present Continuous refers to an action which is in progress at the time of speaking. - I'm writing a letter now. Present Perfect Continuous refers to an action which is either in progress at the time of speaking, or has an effect on the present. - I have been writing letters all day. (I started in the morning and I'm still writing them) Present Continuous: I'm learning English. (at the moment) Present Perfect Continuous: I have been learning English for two years. (I started two years ago and I'm still learning it) Present Continuous: It's raining. (at the moment) Present Perfect Continuous: It has been raining. (the raining stopped a short time ago, but the ground is wet, so the action has an effect on the present)