Is speaking in tongues real, and is it still for today?

The New Testament describes two things sometimes both called "tongues," which is part of why this question gets confusing.

At Pentecost, in Acts 2, people spoke in other real, known human languages so a diverse international crowd could each understand the good news of Jesus in their own language. In 1 Corinthians, Paul describes something that sounds more like a private prayer language used in worship, which Paul says needs interpretation to be understood by others.

Christians disagree about whether either kind continues today. Some, often called cessationists, believe dramatic sign-gifts like tongues were mainly meant to authenticate the earliest apostles and the brand-new church, gradually stopping after that founding period. Others, called continuationists—including most Pentecostal and Charismatic Christians—believe the Holy Spirit still gives this and other gifts today, pointing to Paul's instruction not to "forbid speaking in tongues."

Both sides agree tongues, real or counterfeit, should be tested by whether they build up the church and point to Jesus.