Monday night was the last night to offer arbitration to players. What the heck does that mean? Here (with some aid from here)
Players with at lease three years, but less than six years, of ML service are eligible.
Super-2 players (which is complicated).
Players who have filed for free agency, but the team has to offer and the player has to accept.
Teams have to offer contracts to players by December 12.
Players who have been offered arbitration have to accept by December 7. If they accept, the player goes back on the roster and the two sides continue to negotiate.
If they can't come to an agreement by January, the team and the player separately submit a figure to a three-person panel of arbitrators. At the hearing (and negotiations can continue up to the hearing), each side has one hour to present their case with a 30-minute rebuttal available.
The sides high-low each other, presenting the awkward scenario of a team telling a player they want to play for them how they aren't worth what they think they are. If a free agent is offered arbitration and declines and signs with another team, the team who signs them loses draft picks to the team from which the player departed. If accepted and a deal is struck, it's a one-year/non-guaranteed deal (meaning he can be cut, and is only due 30-45 day termination pay).