The original boots worn for rugby were either hobnail boots or walking boots and most experts see these as the forerunner to the modern day studs. As you can imagine these protrusions could cause quite serious damage and so the first studs were brought in to satisfy law changes which took this into consideration, this happened in 1889, though it was 1910 when the specification became tighter.
The early studs were specified as being no less than 3/4 inch in diameter and no longer than half the diameter, they were typically leather or tight packed felt and fixed to the sole of the boot with 4 nails. The next change occurred in 1926 when studs had to be leather, circular and fixed by at least 3 nails. Rubber was included in 1948, Aluminium in 1953 and approved plastics in 1954.
The studs in use today will normally be either fixed to the boot, not ideal as this means when the studs wear the complete boot must be replaced,or they will be a screw in. studs can be made from aluminium or a hard plastic. The design and materials must conform to the IRB regulation 12 under law 4.3. This specifies that the stud can be no more than 21mm long.
Players should be aware that; Referees must check all players' studs before a game to ensure that they all meet the standrd. Studs that are worn must be replaced before a player can join the game. This is to eliminate the potential for a stud causing a wound.
Generally there are two types of stud pattern worn: the 8 stud or the 6 stud. * The 8 stud is most often worn by the tight forwards (props, hooker and locks) to provide them with extra grip for scrummaging and mauling. The * 6 stud is worn by backs as it allows for more agility and quicker movement around the field. Plastic "blade" studs, common in soccer, are an increasingly frequent choice among backs.