What must an athlete wear to compete?

• Shoes: "Athletes may compete either barefoot or in Athletic Shoes on one or both feet."
• Shoe regulations: shoes must comply with the Athletic Shoe Regulations approved by the World Athletics Council. Those are a separate document, which was not read for these pages.
• Clothing: must be "clean, and designed and worn so as not to be objectionable", and made of material that is "non-transparent even if wet".
• The judges' view: athletes "must not wear clothing which could impede the view of the Judges".
• Team kit: at major competitions athletes wear the uniform approved by their federation.
• Bibs: two, worn on the chest and on the back. Only the jumping events are allowed a single bib.
• Tape on shoes: tape on the outside of a throwing shoe is acceptable and should be shown to the chief judge. Nothing may be sprayed or spread on the shoes.
• As issued: bibs "may not be cut, folded or obscured in any way".
• No bib, no competition: an athlete may not take part without the proper bib or identification.
• Protection: bandages, tape, belts and supports may be worn for protection or for medical reasons.
• The call room: officials there see to it that bibs, shoes and clothing are in order before athletes go out.
• The penalty: an athlete who does not follow these rules and refuses the referee's direction, or competes anyway, is disqualified.

Two bibs let the judges and the results staff identify a thrower from either side of the cage. The clothing rules protect the judges' view of the attempt. Shoes are controlled because the sole decides how a foot grips and turns, so World Athletics approves what may be worn.