The tete-a-tete brings 27 EU leaders together six times a year - and this year there is a special guest.
EU leaders are meeting in Brussels this week to discuss energy prices, COVID-19 and the war in Ukraine.
The meeting is a summit of the European Council, made up of 27 member states and meeting six times a year.
But what is the European Council and what power does it have? And why do its meetings sometimes stretch to more than 80 hours?