Explained: The nature of Ronaldo's international retirement is in stark contrast to his great rival Messi

Cristiano Ronaldo announced his retirement from Portugal's national team via video message on Thursday

Nations League

A UEFA international competition between European national teams, separate from the World Cup and European Championship

Copa America

The main international football championship for South American national teams

Ballon d'Or

An annual award given to the world's best individual football player

GOAT debate

Shorthand for 'greatest of all time' debate, often used to compare Ronaldo and Messi

Euro 2016

The 2016 UEFA European Championship, won by Portugal