A skinsuit is called by that name, because when they are fitted properly the fit is skin-tight. The name skinsuit is used to describe any one piece inline or ice speed skating outfit (or leggings and fitted jersey) made of a stretchy swimsuit-type fabric like lycra or spandex that stretch in all directions.
Skinsuits are important for inline and ice speed skating events, because they help optimize each skater's racing performance. A skater can move faster in a skinsuit because it is aerodynamic and reduces the air resistance around the skater, and also provides more freedom of movement.
There are many skinsuit manufacturers worldwide who produce this type of speed skating wear in many colors and the designs and fabrics often incorporate team logos and graphics. They are usually made by specialists who have the skill needed to make them correctly.