Hi,
There seem to be a range of views from total disbelief people who are familiar with the gift. For those who are interested in the gift then have a read. I think it is pretty self explanatory but if you have questions then please ask.
1 Corinthians 14 (New International Version)
Gifts of Prophecy and Tongues
1Follow the way of love and eagerly desire spiritual gifts, especially the gift of prophecy. 2For anyone who speaks in a tongue[a] does not speak to men but to God. Indeed, no one understands him; he utters mysteries with his spirit.[b] 3But everyone who prophesies speaks to men for their strengthening, encouragement and comfort. 4He who speaks in a tongue edifies himself, but he who prophesies edifies the church. 5I would like every one of you to speak in tongues,[c] but I would rather have you prophesy. He who prophesies is greater than one who speaks in tongues,[d] unless he interprets, so that the church may be edified.
6Now, brothers, if I come to you and speak in tongues, what good will I be to you, unless I bring you some revelation or knowledge or prophecy or word of instruction? 7Even in the case of lifeless things that make sounds, such as the flute or harp, how will anyone know what tune is being played unless there is a distinction in the notes? 8Again, if the trumpet does not sound a clear call, who will get ready for battle? 9So it is with you. Unless you speak intelligible words with your tongue, how will anyone know what you are saying? You will just be speaking into the air. 10Undoubtedly there are all sorts of languages in the world, yet none of them is without meaning. 11If then I do not grasp the meaning of what someone is saying, I am a foreigner to the speaker, and he is a foreigner to me. 12So it is with you. Since you are eager to have spiritual gifts, try to excel in gifts that build up the church.
13For this reason anyone who speaks in a tongue should pray that he may interpret what he says. 14For if I pray in a tongue, my spirit prays, but my mind is unfruitful. 15So what shall I do? I will pray with my spirit, but I will also pray with my mind; I will sing with my spirit, but I will also sing with my mind. 16If you are praising God with your spirit, how can one who finds himself among those who do not understand[e] say "Amen" to your thanksgiving, since he does not know what you are saying? 17You may be giving thanks well enough, but the other man is not edified.
18I thank God that I speak in tongues more than all of you. 19But in the church I would rather speak five intelligible words to instruct others than ten thousand words in a tongue.
20Brothers, stop thinking like children. In regard to evil be infants, but in your thinking be adults. 21In the Law it is written:
"Through men of strange tongues
and through the lips of foreigners
I will speak to this people,
but even then they will not listen to me,"[f] says the Lord.
22Tongues, then, are a sign, not for believers but for unbelievers; prophecy, however, is for believers, not for unbelievers. 23So if the whole church comes together and everyone speaks in tongues, and some who do not understand[g] or some unbelievers come in, will they not say that you are out of your mind? 24But if an unbeliever or someone who does not understand[h]comes in while everybody is prophesying, he will be convinced by all that he is a sinner and will be judged by all, 25and the secrets of his heart will be laid bare. So he will fall down and worship God, exclaiming, "God is really among you!"
Orderly Worship
26What then shall we say, brothers? When you come together, everyone has a hymn, or a word of instruction, a revelation, a tongue or an interpretation. All of these must be done for the strengthening of the church. 27If anyone speaks in a tongue, two—or at the most three—should speak, one at a time, and someone must interpret. 28If there is no interpreter, the speaker should keep quiet in the church and speak to himself and God.
Regards,
Stephen