Using the Present Perfect Tense
The present perfect tense is common in English. It is used for many different functions. This page will explain the most important uses of the present perfect tense.
Use 1: Actions which started in the past and are still continuingThe present perfect is often used for an action which started at some time in the past, and are still continuing now. Often, the words for (with a length of time) and since (with a starting time) are used along with the present perfect.
Use 2: Actions which happened at some unknown time in the pastSometimes, it's important to say that something happened (or didn't happen), but it's not important (or not known) when it happened. In this case, we can use the present perfect too. In this case, we often use the words already, yet, ever or never along with the present perfect. These words usually go before the past participle in the sentence.
Use 3: Actions which happened in the past, but have an effect in the presentThis use is a little more difficult than the other two. In this case, the action happened at some time in the past, but the effect of the action is still important now. It's easiest to understand this use if we compare present perfect sentences with simple past sentences.