The COCOMO model is a widely used software cost estimation model that predicts development effort and schedule based on project attributes. It includes basic, intermediate, and detailed models of increasing complexity. The intermediate model estimates effort as a function of source lines of code and cost drivers. The detailed model further incorporates the impact of cost drivers on development phases. COCOMO 2 expands on this with application composition, early design, reuse, and post-architecture models for different project stages.