UPDATE: The ability to place bounties was suspended on 2020-10-07. This does not prevent players from receiving payouts for existing bounties, but does prevent the creation of any new bounties.
Players may place bounties on other players, corporation or alliances without a specified reason and this will result in a "Wanted" sign being placed on the entity in question. Depending upon how much ISK a 'Wanted' entity loses when destroyed, attackers involved in the destruction may be eligible for a bounty payout.
You can place a bounty by right-clicking the entity of your choice, and selecting "Place Bounty".
Having a bounty does not mean that the entity can be freely attacked. CONCORD will still react on illegal attacks even if they have a player bounty set on them, meaning the usual consequences for illegal attacks apply.
All bounties are final and will not be refunded.