The Bible teaches that in the old days, at the beginning of the Church, this (speaking in tongues) was a Spiritual Gift, given by the Holy Spirit to some Christians. Here a…re only some of the texts in the Bible that mentions this gift : Acts 2:4 "And they were all filled with the Holy Ghost, and began to speak with other tongues, as the Spirit gave them utterance." Acts 10:46 "For they heard them speak with tongues, and magnify God." Acts 19:6 "And when Paul had laid his hands upon them, the Holy Ghost came on them; and they spake with tongues, and prophesied." 1 Corinthians 12:8-11 "For to one is given by the Spirit the word of wisdom; to another the word of knowledge by the same Spirit; To another faith by the same Spirit; to another the gifts of healing by the same Spirit; To another the working of miracles; to another prophecy; to another discerning of spirits; to another divers kinds of tongues; to another the interpretation of tongues: But all these worketh that one and the selfsame Spirit, dividing to every man severally as he will." So the gift was real in the "primary Church". But in our days there are Christians that believe the Holy Spirit gives this gift today, and other Christians don't think that speaking in tongues is "active" today. Of course there are arguments on each side, which one is true needs to be determined by good study of the issue. My advise is from 1 Thessalonians 5:21 "Prove all things; hold fast that which is good.".
While Some would advocate speaking in tongues is meant for all true Christians, the text above in 1 Corinthians 12:8-11 indicates that it was meant for a few in that early church, while other gifts were meant for other members. Bear in mind that the letter to the Church at Corinth was written because of the many problems occurring there over Biblical teaching, tongues speaking being one of the problems. Consider chapters 12-14 in total context with this. Also, the tongues in the New testament were valid languages as seen in Acts 2:6. The word "unknown" was inserted into the English translation in the Corinthian passages mentioned, because the languages were unknown to the people at Corinth. But, they were real languages of other places in the world. Some major tongue speaking advocates of today would maintain that it is unintelligible speech, that of angels as in 1 Corinthians 14:1. Yet, angels never spoke to men in an unintelligible language, nor do they lack ability. The Greek word for tongue in the New Testament is "glossa," which means "language, nothing else. When Paul, in Acts 21:40, defended himself before an unruly crowd, "he spake unto them in the Hebrew tongue (glossa)," which calmed many of the Jewish people. There is among some the consideration that Biblical tongues speaking was a sign for God bringing the Holy Spirit into lives of the Jews (Acts2), the Gentiles (Acts 10, Cornelius' household) and possibly Samaritans (Acts 19:1-7), who were baptized only by Apollo with John the Baptist's type of repentance ( a transition). No other portion, in the 8 years transpiring in Acts, records any speaking in tongues occurring. Some would say that "tongues will cease," means that they have today. Yet, while there is no clear direction to determine that, there is clear instruction, in 1 Corinthians 14, that there should be decency and orderliness in the church's meetings (v. 40), and, if tongues are to be spoken there need to be one tried and true Holy Spirit interpretor, previously known, to interpret or those, who would speak in tongues, are to keep silent. The Pastor, as overseer of the church should ensure this orderliness and decent procedure. It might be observed that today this control does not exist in many circles. In other places, the pastor will not allow the activity, because it is considered not for today or in some cases, he knows there is no valid, tried and true Holy Spirit interpretor. In any case, the local pastor is responsible to God for proper activity within the gathering of God's people, the church. ( Full Answer )