What's in music that brings people together?
The purpose of the previous text is to answer the question asked in the title.
Everybody know music brings people together. Everyone can choose which kind of music he wants to listen to , without any barriers (such as language). People different from each other are joined together by same music tastes.
But why does this happen?
It happens because they like the messages that kind of music sends out.
Even though everyone has a different opinion about music , the feelings transmitted by the same songs can be similar.
At concerts we can see people from all over the world in the same place, everyone enjoying his time and being part of a unique things. Probably the same people in the daily life wouldn't neither look each other.
But music is more just a common pleasure.
It can work to create a sense group identity. On the other hand this groups could "fight" each other, because there are people that think their group is the best.
Taking into consideration all the above, I can say music is an be the common thread between different people.