The present perfect continuous connects the past to the present. We use it when an action started in the past and is still happening now, or has just stopped. 'I have been working on this project since Monday' — it started Monday and is still in progress. 'You look exhausted — have you been sleeping badly?' — we can see the evidence now. With 'for' and 'since': 'She has been studying for three hours' / 'He has been working here since 2020'. Compare with the present perfect simple: 'I have written ten emails today' — completed. 'I have been writing emails all morning' — ongoing, with emphasis on the activity itself.

💡 Did you know? English is one of very few languages with a present perfect continuous tense. Most European languages use simpler tenses to express the same ideas — which is why this tense is particularly hard to master for many learners.