This is the team put together by Chief Executive Creator BRAHMA to expedite cosmic matters during construction of the Universe. Not many creator gods ask for assistance, but BRAHMA in his wisdom opted for a bit of extra help. The PRAJAPATIS were created to assist with various administrative tasks — road-testing the Laws of Physics, sorting out what planet should go where, and so on.
Originally worshipped as a single deity, they became known as a team when BRAHMA took over the top god spot. Their membership varies depending on who you ask — ten or eleven is the usual number but the Mahabharata mentions fourteen and we have seen references to twenty-one or more. Probably half of them are on a freelance contract.
Some may even have been sacked. Which one was responsible for flowers on the moon? Several of the most impressive deities went on to greater things.