A player option is an optional year at the end of a contract that can be applied at the player's discretion. In such cases, the player has the right to exercise his option and lock in that optional salary as a guaranteed sum or reject the option in favor of testing free agency.
Following the 2014 season, right-hander Dan Haren exercised a $10 million player option on his contract to remain with the Dodgers (although he was ultimately traded to the Marlins prior to the '15 season). Conversely, Royals outfielder Alex Gordon declined a $14 million player option following the '15 season and tested the free-agent market in search of a larger contract. He went on to re-sign with the Royals on a four-year, $72 million deal.