Function-point (FP) based estimation technique is very popular estimation technique to estimate project cost, and effort.
FP are derived using an empirical relationship based on countable measures of software's informationdomain and assessments of software complexity.
How it can be used?
Decomposition for FP-based estimation focus on information domain values, rather than software function. Project planner focus on each of the information domain characteristics like, input, output, data files, inquiries, and external interfaces. The resultant estimates are used to derived a FP value that can be tied to past data and used to generate an estimate.