A time and materials contract is a type of agreement used in project management where the client pays for the actual time spent by workers and the materials used in a project. This contract is beneficial when the scope of work is uncertain, allowing flexibility as the project progresses. In this arrangement, the contractor typically charges an hourly rate for labor and adds the cost of materials, plus any additional expenses. This approach helps ensure that the client only pays for the work done and materials used, making it suitable for projects with changing requirements or unclear specifications.