Teams in Olympic Football?

Question

How is it decided which teams will take part in the Olympic Football?

Brazil are there but World Champions Italy are not. Were Italy knocked out in a qualifying round? Some of the teams on the list are not known for their footballing skills.

Answer 1

Italy lost 3-2 to Belgium. Remember, it's not the full team that plays it's an under 21 team with 3 over-age players allowed.