Glossary
Overtime
In one line: Extra rounds when a match reaches 12-12: play continues until one team is two rounds ahead.
What it means
A competitive match is won by reaching 13 rounds. At 12-12 the game goes to overtime: rounds are played in pairs, one on attack and one on defense, until one team is two rounds ahead. Every overtime round starts everyone with the same money, so the economy does not matter: whoever plays that round better wins it.
In competitive, players can also vote to end the match in a draw during overtime. Unrated matches usually play a single deciding round instead.
An example
It is 12-12. First overtime round on attack: you win it, 13-12. You lose the defense round: 13-13, the pair starts again. You win both of the next two: 15-13, match over.