Don't be fooled by what you see in operation today by people claiming to have this gift. Tongues was a gift given by the Holy Spirit for no other reason than to preach the gospel to unbelieving jews in their own language. How do we know that? In the book of Isaiah which was written 1000 years before the gift was given at Pentecost, the Lord was specifically speaking about the Jews where it states"with men of stammering lips and other tongues will I speak to this people" here the Lord states that it was for specific use to speak to the jews and this happened at the time of Pentecost as the Bible records that there were jews, devout men,gathered from every nation under heaven. when they heard the gospel being preached in their own language, they remembered the prophesy in Isaiah and glorified God. Here, they all marveled because all the men speaking were all from Galilee so the crowd realised that as they were all speaking different languages, and they were all hearing the gospel in their own native language, the prophesy was being fulfilled. This gift is not in operation today as the Scriptures tell us that where there are tongues, they shall cease. We note from today's so-called tongues speakers, it is nothing more than a cheap imitation of the real gift as they babble in some ecstatic gibberish which is unknown to be any language on earth and we note also that there is no unbelieving Jew present and no interpreter. Why have an interpreter present if the hearer understands perfectly what is being said by the speaker? he is there to tell both the church and the speaker what is being said and not for the benefit of the unbelieving Jew. This gift was where the Holy Spirit would speak through the person in a known language without the speaker ever having learned the language and it could not be turned on at the command of the speaker as the bible records that these men spoke as the Spirit gave utterance. I hope this has helped you. God Bless!