Glossary
Default
In one line: On attack, spreading across the map to gather information and space before choosing a site.
What it means
A default is the "standard" start to an attacking round: instead of everyone going to one site together, the team spreads out, each player controls an area, takes space and gathers information. Then, mid-round, the team decides where to go.
The point is to ask the defense a question: where are you? how many on each site? who rotated? The answers decide the rest of the round. A bad default is five scattered players waiting without knowing what they are looking for.
An example
On Haven the team splits: two players at A long, one in mid, two near C. Nobody commits, but everyone holds a piece of the map. At 50 seconds you know A has three defenders and C only one: the round goes to C.