roller skates

A pair of roller skates

Roller skates are boots with wheels mounted to the bottom, allowing the user to travel on hard surfaces similarly to an ice skater on ice. The first roller skate was an inline skate design, effectively an ice skate with a line of wheels replacing the blade. In modern usage, the term typically refers to skates with two pairs of wheels on shared axles like those of skateboards (early versions of which were made using roller skate parts). Skates with this configuration are also known as "quad skates" or "quads" and, like skateboards, steer by tilting the skate to one side, which causes the axles to turn inward.