On what basis is cucumber's runner is runnin respective clas

Sir,

Am watching video part1 of cucumber module...

there are 3 things:
1>feature file
2>HolyTester class[which has annotations tied to methods]
3>HolyITPeople[Runner class]

in runner class there's no mention of which class to run..
@RunWith(Cucumber.class)
public void runIT(){
}


[b:1aqj3vzq]Query:How does this runIT(){} know , it has to run respective HolyTester,HolyITPeople files?
No mention of name or anything?[/b:1aqj3vzq]