bottom-up estimation

Bottom-up and top-down software project estimation are two approaches used to estimate the cost and time required for a project. In bottom-up estimation, the project is broken down into smaller tasks, and each task is estimated individually before aggregating the total estimate. On the other hand, top-down estimation involves coming up with a high-level estimate based on previous similar projects or expert judgment. Bottom-up estimation offers more accuracy but requires more time and effort, while top-down estimation is quicker but less accurate. Both approaches have their pros and cons, and the choice between them depends on the specific project requirements.