Europol deals with crimes that threaten EU citizens and the common interests of the EU; this includes serious and organised crime and terrorism. In a nutshell, we make Europe safer. A simple concept, but actually challenging in practice.
If a crime affects two or more Member States, we can assist law enforcement in joining the dots and help investigators in their work. The EU has 28 Member States, but each Member State has a number of law enforcement authorities (in the EU alone there are around 90 separate authorities). Europol brings them together to fight crime as one. This makes Europol the EU hub for criminal intelligence.