Defect density is a measure used in software engineering to quantify the number of defects or bugs in a software product relative to its size. It is typically calculated by dividing the total number of defects by the size of the software, which can be measured in lines of code (LOC) or function points. This metric helps teams assess the quality of their software and identify areas that may need improvement. By analyzing defect density, organizations can track the effectiveness of their testing processes and development practices over time. A lower defect density indicates a higher quality product, while a higher density may signal the need for more rigorous testing or code reviews. This metric is essential for maintaining software quality and ensuring customer satisfaction.