The Present Perfect Continuous (also called the Present Perfect Progressive) is used to talk about something that began in the past and continues until now. You may notice that this is also one of the three functions of the Present Perfect tense. This can be a little confusing for ESL or EFL students.
The thing to point out to English language learners is that the Present Perfect Continuous is used when you want to emphasize the duration of the activity that began in the past.
The structure of the Present Perfect Continuous is this:
More information on the Present Perfect Continuous.