What are quarterfinals?

Some articles on quarterfinals:

Jamaica At The 1984 Summer Olympics - Results By Event - Athletics
... Men's 400 metres Bertland Cameron Heat — 46.14 Quarterfinals — 45.15 Semifinals — 45.10 (→ advanced to final did not run due to injury) Devon Morris Heat — 45.80 Quarterfinals — 46.14 (→ did not advance ...
Elena Dementieva - Tennis Career - 2007: Dropping Out of The Top 10
... Dementieva won two titles, reached three semifinals and five quarterfinals, and reached the fourth round at the Australian Open ... later, she lost to Bartoli again in the quarterfinals of the tournament in Eastbourne, United Kingdom 6–1, 6–0 ... tournaments in San Diego and New Haven, Connecticut and the quarterfinals of the tournament in Los Angeles, but lost early at the Tier I Rogers Cup in Toronto and at the US Open ...
FIFA World Cup Records - Attendance - Total and Average Attendance
... Round 1 8,000 Semi-finals 60,000 21,059 18. 483,000 Quarterfinals 6,846 Quarterfinals 58,455 26,833 22. 1,043,500 Round 1 4,000 Final 199,854 47,432 26. 889,500 Round 1 3,000 ...