What estimation method is based on the functionalities of a system?

The function point estimation method is specifically designed to measure the functionalities delivered by a software system. It quantifies the functions provided to the user based on the system's features, such as inputs, outputs, user interactions, and data files. By evaluating these aspects, function point analysis helps in estimating the size and complexity of the software, which can then be translated into resources, time, and cost estimates for development projects.

This method emphasizes the functional requirements rather than the technical aspects, making it a widely accepted approach for assessing the value and effort required for different software functions. It provides a clear, objective basis for estimation that can be applied consistently, allowing for better planning and resource allocation in project management. As a result, it aligns estimation closely with the actual functionalities that are to be delivered to the end-users.