Bounty is a set part of the award kept aside for people promoting the project, these people are paid some coins/ tokens from the total supply for the services that they have performed. Generally, there are set stakes for every activity that a person does, and based on the stakes of every person, a person gets his share from the total bounty pool.

For example A bounty pool for XYZ Coin has 1 Million Coins, 1 week of the signature campaign gives 10 Stakes to Senior members and 5 stakes for members, Now after 4 weeks, A senior member who works all 4 weeks will have 40 Stakes(10 x 4) while Member who let's say just worked for 2 weeks would have 20 stakes( 5 x 2). Out of a total pool of 1 Million coins, the distribution would be 800k coins to Senior Member and 200k to Member.

Now the person who does all this calculation of staking, creates the bounty thread and manages it, and also ensures everyone is obeying the rules of the bounty and project is called the Bounty Manager.