Bottom-Up Estimation is a project management technique used to estimate the total cost or duration of a project by breaking it down into smaller, manageable components. Each component is assessed individually, and the estimates are then aggregated to form a complete picture. This method allows for more accurate estimates as it considers the specific details of each task. This approach is often contrasted with Top-Down Estimation, where the overall project is estimated first, and then divided into parts. Bottom-Up Estimation is particularly useful in complex projects, as it encourages thorough analysis and can help identify potential risks early in the planning process.