What is the “Spitzenkandidaten”?

To determine who the next President of the European Commission will be, the “Spitzenkandidaten” process is used. Mirroring national elections, political groups in the European Parliament appoint lead candidates who all compete for the position. The leader of the group most capable of marshalling enough parliamentary support typically goes on to become head of the Commission. But as the process isn’t legally binding, it is not always respected.