Milestone billing is a type of billing that product development projects often use. In general, milestone billing means that the project is billed based on specific milestones that are reached during the product development process. This type of billing can be beneficial for both the product development team and the client, as it provides a clear overview of the project's progress and ensures that all parties are aware of what work has been completed. Additionally, milestone billing can help to ensure that the product development process stays on track and that everyone involved knows exactly what needs to be done in order to reach the next milestone. Ultimately, milestone billing can help to make product development projects more efficient and streamlined.