who can explain me the nesting concept?

[stefanocps]

hello after getting quite good with edius and premiere, i am trying to go with avid. and i must say. it is the one i like best!
studyng and trying, i have come across the concept of nesting effect, step in step out...it is somethinf i cannot really grab
who wouild give me some help?
thanks

[video652]

Nesting allows you to apply multiple effects to one clip.