From what product must the acceptance criteria for a project is derived and why?

The acceptance criteria must be derived by the Requirements Specification that is where the users’ stated desires are documented. The real acceptance criteria may not essentially be defined within the Requirements Specification that might thereby become too large and unwieldy, nevertheless this is important to make the needs as exact and measurable as probable to avoid later arguments over acceptance; for illustration, ‘a response time of less than two seconds for 90 percent of transactions’ is a large number more precise than ‘a fast response time’. As the acceptance criteria are based onto the Requirements Specification, such emphasises the significance of that document.