(Webster) Glossolalia: an ecstatic utterance of unintelligible speechlike sounds, viewed by some as a manifestation of deep religious experience.  Copyright (c) 1992 Grolier Electronic Publishing, Inc.

Speaking in tongues (Glossolalia) is a Christian religious phenomenon in which the believer, in an ecstatic state, speaks in a foreign language or utters unintelligible sounds that are taken to contain a divine message. Many Christians believe the genuine gift of tongues to have been confined to earliest Christianity, at PENTECOST, and during conversion experiences. Modern revivalist movements such as the Pentacostalists and Charismatics believe it to be given in contemporary times as a testimony to the special presence of the HOLY SPIRIT. Many psychologists explain the  phenomenon as a hypnotic trance that results from religious excitement.

Paul Merritt Bassett: Bibliography: Goodman, F. D., Speaking in Tongues (1972); Kelsey, Morton T., Tongue-Speaking (1964; repr. 1981); Mills, Watson E., ed., Speaking in Tongues (1986); Samarin, W. J., Tongues of Men and Angels (1972).

[Mark 16:15-16:20] And He said to them, "Go into all the world and preach the gospel to all creation. "He who has believed and has been baptized shall be saved; but he who has disbelieved shall be condemned. "And these signs will accompany those who have believed: in My name they will cast out demons, they will speak with new tongues; they will pick up serpents, and if they drink any deadly poison, it shall not hurt them; they will lay hands on the sick, and they will recover." So then, when the Lord Jesus had spoken to them, He was received up into heaven, and sat down at the right hand of God. And they went out and preached everywhere, while the Lord worked with them, and confirmed the word by the signs that followed. And they promptly reported all these instructions to Peter and his companions. And after that, Jesus Himself sent out through them from east to west the sacred and imperishable proclamation of eternal salvation. [NAS]

CONSIDERATION SHOULD BE GIVEN FOR "ACTS" BEING A BOOK OF RECORDED HISTORY. (THE BOOK IS NOT MEANT TO LAY OUT A SET OF RULES FOR FUTURE READERS.) THE BOOK IS A RECORDING OF ACTIVITIES, IE., ACTS. (there are other non historical books laying out the how come and how to's of tongues)

[Acts 2:1-2:47] And when the day of Pentecost had come, they were all together in one place. And suddenly there came from heaven a noise like a violent, rushing wind, and it filled the whole house where they were sitting. And there appeared to them tongues as of fire distributing themselves, and they rested on each one of them. And they were all filled with the Holy Spirit and began to speak with other tongues, as the Spirit was giving them utterance. Now there were Jews living in Jerusalem, devout men, from every nation under heaven. And when this sound occurred, the multitude came together, and were bewildered, because they were each one hearing them speak in his own language. And they were amazed and marveled, saying, "Why, are not all these who are speaking Galileans? And how is it that we each hear them in our own language to which we were born? "Parthians and Medes and Elamites, and residents of Mesopotamia, Judea and Cappadocia, Pontus and Asia, Phrygia and Pamphylia, Egypt and the districts of Libya around Cyrene, and visitors from Rome, both Jews and proselytes, Cretans and Arabs - we hear them in our own tongues speaking of the mighty deeds of God." And they all continued in amazement and great perplexity, saying to one another, "What does this mean?" But others were mocking and saying, "They are full of sweet wine." But Peter, taking his stand with the eleven, raised his voice and declared to them: "Men of Judea, and all you who live in Jerusalem, let this be known to you, and give heed to my words. "For these men are not drunk, as you suppose, for it is only the third hour of the day; but this is what was spoken of through the prophet Joel:

‘And it shall be in the last days,’ God says,’ That I will pour forth of My Spirit upon all mankind; And your sons and your daughters shall prophesy, And your young men shall see visions, And your old men shall dream dreams; Even upon My bondslaves, both men and women, I will in those days pour forth of My Spirit And they shall prophesy. ‘And I will grant wonders in the sky above, And signs on the earth beneath, Blood, and fire, and vapor of smoke. ‘The sun shall be turned into darkness, And the moon into blood, Before the great and glorious day of the Lord shall come. ‘And it shall be, that everyone who calls on the name of the Lord shall be saved.’ 

"Men of Israel, listen to these words: Jesus the Nazarene, a man attested to you by God with miracles and wonders and signs which God performed through Him in your midst, just as you yourselves know - this Man, delivered up by the predetermined plan and foreknowledge of God, you nailed to a cross by the hands of godless men and put Him to death. "And God raised Him up again, putting an end to the agony of death, since it was impossible for Him to be held in its power. "For David says of Him, ‘I was always beholding the Lord in my presence; For He is at my right hand, that I may not be shaken. ‘Therefore my heart was glad and my tongue exulted; Moreover my flesh also will abide in hope; Because Thou wilt not abandon my soul to Hades, Nor allow Thy Holy One to undergo decay. ‘Thou hast made known to me the ways of life; Thou wilt make me full of gladness with Thy presence.’ "Brethren, I may confidently say to you regarding the patriarch David that he both died and was buried, and his tomb is with us to this day. "And so, because he was a prophet, and knew that God had sworn to him with an oath to seat one of his descendants upon his throne, he looked ahead and spoke of the resurrection of the Christ, that He was neither abandoned to Hades, nor did His flesh suffer decay. "This Jesus God raised up again, to which we are all witnesses. "Therefore having been exalted to the right hand of God, and having received from the Father the promise of the Holy Spirit, He has poured forth this which you both see and hear. "For it was not David who ascended into heaven, but he himself says: ‘The Lord said to my Lord," Sit at My right hand, Until I make Thine enemies a footstool for Thy feet. "Therefore let all the house of Israel know for certain that God has made Him both Lord and Christ - this Jesus whom you crucified." Now when they heard this, they were pierced to the heart, and said to Peter and the rest of the apostles, "Brethren, what shall we do?" And Peter said to them, "Repent, and let each of you be baptized in the name of Jesus Christ for the forgiveness of your sins; and you shall receive the gift of the Holy Spirit. "For the promise is for you and your children, and for all who are far off, as many as the Lord our God shall call to Himself." And with many other words he solemnly testified and kept on exhorting them, saying, "Be saved from this perverse generation!" So then, those who had received his word were baptized; and there were added that day about three thousand souls. And they were continually devoting themselves to the apostles’ teaching and to fellowship, to the breaking of bread and to prayer. And everyone kept feeling a sense of awe; and many wonders and signs were taking place through the apostles. And all those who had believed were together, and had all things in common; and they began selling their property and possessions, and were sharing them with all, as anyone might have need. And day by day continuing with one mind in the temple, and breaking bread from house to house, they were taking their meals together with gladness and sincerity of heart, praising God, and having favor with all the people. And the Lord was adding to their number day by day those who were being saved. [NAS]

Acts 19:1-19:6] And it came about that while Apollos was at Corinth, Paul having passed through the upper country came to Ephesus, and found some disciples, and he said to them, "Did you receive the Holy Spirit when you believed?" And they said to him, "No, we have not even heard whether there is a Holy Spirit." And he said, "Into what then were you baptized?" And they said, "Into John’s baptism." And Paul said, "John baptized with the baptism of repentance, telling the people to believe in Him who was coming after him, that is, in Jesus." And when they heard this, they were baptized in the name of the Lord Jesus. And when Paul had laid his hands upon them, the Holy Spirit came on them, and they began speaking with tongues and prophesying.

[1 Corinthians 12:1-14:25] Now concerning spiritual gifts, brethren, I do not want you to be unaware. You know that when you were pagans, you were led astray to the dumb idols, however you were led. Therefore I make known to you, that no one speaking by the Spirit of God says, "Jesus is accursed"; and no one can say, "Jesus is Lord," except by the Holy Spirit. Now there are varieties of gifts, but the same Spirit. And there are varieties of ministries, and the same Lord. And there are varieties of effects, but the same God who works all things in all persons. But to each one is given the manifestation of the Spirit for the common good. For to one is given the word of wisdom through the Spirit, and to another the word of knowledge according to the same Spirit; to another faith by the same Spirit, and to another gifts of healing by the one Spirit, and to another the effecting of miracles, and to another prophecy, and to another the distinguishing of spirits, to another various kinds of tongues, and to another the interpretation of tongues. But one and the same Spirit works all these things, distributing to each one individually just as He wills. For even as the body is one and yet has many members, and all the members of the body, though they are many, are one body, so also is Christ. For by one Spirit we were all baptized into one body, whether Jews or Greeks, whether slaves or free, and we were all made to drink of one Spirit. For the body is not one member, but many. If the foot should say, "Because I am not a hand, I am not a part of the body," it is not for this reason any the less a part of the body. And if the ear should say, "Because I am not an eye, I am not a part of the body," it is not for this reason any the less a part of the body. If the whole body were an eye, where would the hearing be? If the whole were hearing, where would the sense of smell be? But now God has placed the members, each one of them, in the body, just as He desired. And if they were all one member, where would the body be? But now there are many members, but one body. And the eye cannot say to the hand, "I have no need of you"; or again the head to the feet, "I have no need of you." On the contrary, it is much truer that the members of the body which seem to be weaker are necessary; and those members of the body, which we deem less honorable, on these we bestow more abundant honor, and our unseemly members come to have more abundant seemliness, whereas our seemly members have no need of it. But God has so composed the body, giving more abundant honor to that member which lacked, that there should be no division in the body, but that the members should have the same care for one another. And if one member suffers, all the members suffer with it; if one member is honored, all the members rejoice with it. Now you are Christ’s body, and individually members of it. And God has appointed in the church, first apostles, second prophets, third teachers, then miracles, then gifts of healings, helps, administrations, various kinds of tongues. All are not apostles, are they? All are not prophets, are they? All are not teachers, are they? All are not workers of miracles, are they? All do not have gifts of healings, do they? All do not speak with tongues, do they? All do not interpret, do they? But earnestly desire the greater gifts. And I show you a still more excellent way. If I speak with the tongues of men and of angels, but do not have love, I have become a noisy gong or a clanging cymbal. And if I have the gift of prophecy, and know all mysteries and all knowledge; and if I have all faith, so as to remove mountains, but do not have love, I am nothing. And if I give all my possessions to feed the poor, and if I deliver my body to be burned, but do not have love, it profits me nothing. Love is patient, love is kind, and is not jealous; love does not brag and is not arrogant, does not act unbecomingly; it does not seek its own, is not provoked, does not take into account a wrong suffered, does not rejoice in unrighteousness, but rejoices with the truth; bears all things, believes all things, hopes all things, endures all things. Love never fails; but if there are gifts of prophecy, they will be done away; if there are tongues, they will cease; if there is knowledge, it will be done away. For we know in part, and we prophesy in part; but when the perfect comes, the partial will be done away. When I was a child, I used to speak as a child, think as a child, reason as a child; when I became a man, I did away with childish things. For now we see in a mirror dimly, but then face to face; now I know in part, but then I shall know fully just as I also have been fully known. But now abide faith, hope, love, these three; but the greatest of these is love. Pursue love, yet desire earnestly spiritual gifts, but especially that you may prophesy. For one who speaks in a tongue does not speak to men, but to God; for no one understands, but in his spirit he speaks mysteries. But one who prophesies speaks to men for edification and exhortation and consolation. One who speaks in a tongue edifies himself; but one who prophesies edifies the church. Now I wish that you all spoke in tongues, but even more that you would prophesy; and greater is one who prophesies than one who speaks in tongues, unless he interprets, so that the church may receive edifying. But now, brethren, if I come to you speaking in tongues, what shall I profit you, unless I speak to you either by way of revelation or of knowledge or of prophecy or of teaching? Yet even lifeless things, either flute or harp, in producing a sound, if they do not produce a distinction in the tones, how will it be known what is played on the flute or on the harp? For if the bugle produces an indistinct sound, who will prepare himself for battle? So also you, unless you utter by the tongue speech that is clear, how will it be known what is spoken? For you will be speaking into the air. There are, perhaps, a great many kinds of languages in the world, and no kind is without meaning. If then I do not know the meaning of the language, I shall be to the one who speaks a barbarian, and the one who speaks will be a barbarian to me. So also you, since you are zealous of spiritual gifts, seek to abound for the edification of the church. Therefore let one who speaks in a tongue pray that he may interpret. For if I pray in a tongue, my spirit prays, but my mind is unfruitful. What is the outcome then? I shall pray with the spirit and I shall pray with the mind also; I shall sing with the spirit and I shall sing with the mind also. Otherwise if you bless in the spirit only, how will the one who fills the place of the ungifted say the "Amen" at your giving of thanks, since he does not know what you are saying? For you are giving thanks well enough, but the other man is not edified. I thank God, I speak in tongues more than you all; however, in the church I desire to speak five words with my mind, that I may instruct others also, rather than ten thousand words in a tongue. Brethren, do not be children in your thinking; yet in evil be babes, but in your thinking be mature. In the Law it is written, "By men of strange tongues and by the lips of strangers I will speak to this people, and even so they will not listen to Me," says the Lord. So then tongues are for a sign, not to those who believe, but to unbelievers; but prophecy is for a sign, not to unbelievers, but to those who believe. If therefore the whole church should assemble together and all speak in tongues, and ungifted men or unbelievers enter, will they not say that you are mad? But if all prophesy, and an unbeliever or an ungifted man enters, he is convicted by all, he is called to account by all; the secrets of his heart are disclosed; and so he will fall on his face and worship God, declaring that God is certainly among you. What is the outcome then, brethren? When you assemble, each one has a psalm, has a teaching, has a revelation, has a tongue, has an interpretation. Let all things be done for edification. If anyone speaks in a tongue, it should be by two or at the most three, and each in turn, and let one interpret; but if there is no interpreter, let him keep silent in the church; and let him speak to himself and to God. And let two or three prophets speak, and let the others pass judgment. But if a revelation is made to another who is seated, let the first keep silent. For you can all prophesy one by one, so that all may learn and all may be exhorted; [NAS]

[1PETER 4:9-11] Be hospitable to one another without complaint. As each one has received a special gift, employ it in serving one another, as good stewards of the manifold grace of God. Whoever speaks, let him speak, as it were, the utterances of God; whoever serves, let him do so as by the strength which God supplies; so that in all things God may be glorified through Jesus Christ, to whom belongs the glory and dominion forever and ever. Amen. [NAS]

After Paul tells us how much better all the other gifts are than tongues and all the wrong ways to do it, he says "do not forbid it." [1 Cor 14:39] Therefore, my brethren, desire earnestly to prophesy, and do not forbid to speak in tongues. [NAS]