How do the standby lines work?

[luvmytwins02]

Ok this may be a silly question. How do people in the stand by lines ever get on the ride? I guess I dont understand...if there r people in the fast pass line do they ALL get in first, before standby people?
Last time we went it was in feb and we had NO lines...walked on everything. We go in 2 weeks and I am preparing for longer waits

 

[Jennasis]

The CM's allow a certain number of SB people to board and then then a certain number of FP holders. Not sure of the exact ratio.

 

[luvmytwins02]

Gotcha...thanks