Explorers wear a variety of badges:
Membership badge - similar badges are worn by every one of the millions of Scouts around the world.
Country, Region, District and Troop and Patrol badges (so they remember where they belong).
Activity badges which they earn by completing different activities. At Explorer level each badge will take effort by the individual Explorer and is a significant achievement.
Chief Scout's Platinum (linked with Bronze DofE)
Chief Scout's Diamond (linked with Silver DofE)
Queen's Scout Award (linked with Gold DofE)