**Title:** Discovering dual groups

**Abstract:** Compact quantum groups are a well-known way of generalizing the concept of a group in the framework of non-commutative mathematics. Less known are dual groups. Introduced by Voiculescu in the 80s and also known as H-algebras, they are very similar to compact quantum groups but the comutliplication has values this time in a free product instead of a tensor product.

We will introduce the notion of dual group, compare it to compact quantum groups and give some new results that allow us to understand them better.