What are semifinals?

Some articles on semifinals:

Australia At The 2004 Summer Olympics - Badminton
... Men Athlete Event Round of 32 Round of 16 Quarterfinals Semifinals Final Rank Stuart Brehaut Singles Lee (KOR) L 3-15, 2-15 Did not advance Ashley Brehaut Travis Denney Doubles Panvisvas/Teerawiwatana (TH ...