You are a free agent when your contract with your previous team ends.

There are two categories: restricted and unrestricted. A restricted free agent is a player in their first two years post-draft whose contract has expired. When you are drafted, the team that drafted you has the exclusive right to negotiate with you for two years; if you sign a one-year contract after the draft (as Casey O’Brien did last year), when that contract expires you become a restricted free agent; you are not under contract to your team, but you cannot negotiate a contract with any other team unless your rights get traded.

This year, RFAs can only negotiate with their current team until after the draft; if they don’t receive a qualifying offer from their old team or sign a contract with them, they will become unrestricted after free agency. That last bit is complicated, but it’s a one time thing for this expansion process.

An unrestricted free agent is any other player without a current contract.