There are various types of sparring in the Taekwon-Do training syllabus. BUTF/ITF style sparring is strictly "no-contact" for beginners and "semi-contact" for all other levels. Before a beginner should be allowed to "free spar" they should be able to judge distance between themselves and their opponent and learn to exercise control. This can be practised in 3-Step and 2-Step sparring, where, attacking, defending and counter-attacking moves are all pre-arranged.  In Free Sparring all attacks are delivered above the waist, to the front and side of the body, but not to the back, although any part of the head is a "valid" target. Hence the need to exercise control.
Various items of sparring kit are worn. Not so opponents can use contact but to minimise the risk of injury if contact is made. Contrary to popular belief injuries are rare and a far higher percentage of people injure themselves playing sports like football or rugby.