Kinds of tongues and their interpretation

1 Corinthians 12:10 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: 

The word tongue simply means language. There are known and unknown languages. By known I mean those which are understood by men like English, Swahili etc. Unknown are those not understood by men or are tongues of angels. The speaker of them doesn't understand what they are but they speak out by Faith. Now it also means that the tongue maybe unknown to the speaker yet it's known by some in the congregation. 

Now there is a general gift given to every believer to speak in tongues but this one is specially given to someone by the Holy Spirit to be able to speak in various kinds of tongues. 

The reason we speak in tongues is to edify ourselves spiritually. While the reason for interpretation of tongues is to edify the congregation. Unless when everyone in the meeting is able to speak in tongues, it's well for all of us to pray in tongues. But if there's one who cannot then it's best to interpret the tongues one speaks so that they maybe edified too.  

It's usual for men who are leading a meeting to unknowingly mix the known and unknown languages while praying in tongues. It's a Holy Spirit moment who is interpreting what is being spoken in the unknown tongue though sometimes people never know. It's good they become conscious of it because that's a message being communicated to the body which has gathered. 

EK