Players in the National Hockey League wear equipment which allows their team affiliation to be easily identified, unifying the image of the team. Currently, NHL equipment consists of a hockey jersey, hockey pants, socks, gloves, and a helmet.
Historically, the only standardized piece of the equipment has been the sweater (jersey), which has to be of identical design by the same company for all members of a team. Other elements merely have a number scheme, allowing individual players to select their own brand and model colored to match the uniform but not necessarily identical in appearance. Sticks and other equipment worn under the clothes have no requirements in terms of matching a team's colors; teams will sometimes provide players with team-brand undershirts or other under-clothing, but players are not required or limited to wearing them.
Goalies often have their pads and gloves and masks colored to match the team's color scheme, but there is no requirement for this equipment to match, and goalies who transfer to a new team often play in their old equipment until new colors can be obtained. Alternatively, players who transfer teams have sometimes had their gloves painted temporarily to match the required colors, and are given new helmets.
Each is currently required to have two sweater designs: One with a white base (or sometimes historically, a light color), and one with a darker-colored base. Between the 1970-71 and 2002-03 seasons, NHL teams wore white uniforms at home and dark uniforms on the road (which is the current convention in some low-level ice hockey leagues). Since the 2003–04 season, NHL teams typically wear the dark color at home and the white for road games; there are occasional single-game exceptions. The only element allowed by NHL rules to be interchangeable between the two sets of equipment is the pants.
Starting in 1995 (excluding a few prior isolated instances), some teams began to design a third sweater, or alternate sweater, which allowed them to experiment with new designs, or throwback to a vintage design. Though they are termed third sweaters, they can actually entail an entirely separate look from the primary equipment, often including alternate socks, and sometimes alternate helmets and other equipment. Some third sweaters have eventually become the bases for new primary sweater designs.