Help with a baseball rule!

[DieHardCubbie]

I've seen this alot and cannot find a non-complicated answer.
What is a Rule 5 player?

[EricF]

A Rule 5 player is one who is left unprotected at the Winter Meetings and can be drafted by another team. The drafting team must pay $50,000 for the right to the player. If the player is not kept on the major league roster for the next year, the team that originally had the player can claim him back for $25,000.