Below is an extract from IFAB's Laws of the Game
A player must not use equipment or wear anything that is dangerous.
All items of jewellery (necklaces, rings, bracelets, earrings, leather bands, rubber bands, etc.) are forbidden and must be removed. Using tape to cover jewellery is not permitted.
The players must be inspected before the start of the match and substitutes before they enter the field of play. If a player is wearing or using unauthorised/dangerous equipment or jewellery the referee must order the player to:
• remove the item
• leave the field of play at the next stoppage if the player is unable or unwilling to comply
A player who refuses to comply or wears the item again must be cautioned.
The compulsory equipment of a player comprises the following separate items:
• a shirt with sleeves
• socks – tape or any material applied or worn externally must be the same colour as that part of the sock it is applied to or covers
• shinguards – these must be made of a suitable material to provide reasonable protection and covered by the socks
Goalkeepers may wear tracksuit bottoms.
A player whose footwear or shinguard is lost accidentally must replace it as soon as possible and no later than when the ball next goes out of play; if before doing so the player plays the ball and/or scores a goal, the goal is awarded.
• The two teams must wear colours that distinguish them from each other and the match officials
• Each goalkeeper must wear colours that are distinguishable from the other players and the match officials
• If the two goalkeepers’ shirts are the same colour and neither has another shirt, the referee allows the match to be played.
Undershirts must be:
• a single colour which is the same colour as the main colour of the shirt sleeve; or
• a pattern/colours which exactly replicate(s) the shirt sleeve
Undershorts/tights must be the same colour as the main colour of the shorts or the lowest part of the shorts – players of the same team must wear the same colour.
Non-dangerous protective equipment, for example headgear, facemasks and knee and arm protectors made of soft, lightweight padded material is permitted as are goalkeepers’ caps and sports spectacles.
Where head covers (excluding goalkeepers's caps) are worn, they must:
• be black or the same main colour as the shirt (provided that the players of the same team wear the same colour)
• be in keeping with the professional appearance of the player’s equipment
• not be attached to the shirt
• not be dangerous to the player wearing it or any other player (e.g. opening/closing mechanism around neck)
• not have any part(s) extending out from the surface (protruding elements)