Rookie cards refer to players’ first cards once they make their Major League debut. In most cases, rookie cards are stamped with some kind of designation (e.g. “RC”) on the front or back, and that designation will appear on the card that same year as the debut or, in some cases, the following year.
Players can have dozens of rookie cards – especially if they are a highly-touted prospect that manufacturers want to feature in their products. Rookie cards are highly coveted by collectors and tend to be much more valuable than cards produced later in a player’s career. If a player has several different rookie cards, they will usually vary in value, and collectors will reach a consensus as to which rookie card is most important – and thus, most valued.