Code coverage is a fundamental testing metric that shows which parts of an application’s codebase are executed when tests are run, helping teams understand how thoroughly their software is being validated. By mapping test execution to source code, code coverage reveals untested paths, conditional logic that is never exercised, and areas of the system that may silently accumulate risk over time. This visibility is especially useful in large or fast-changing codebases, where manual review alone cannot reliably catch testing gaps.

Used thoughtfully, code coverage acts as a decision-support tool rather than a simple percentage to optimize. It guides teams toward improving test depth, prioritizing high-impact code for additional testing, and maintaining confidence during refactoring or feature expansion. While it does not guarantee defect-free software, code coverage provides a clear, objective foundation for building stronger, more reliable test strategies when combined with sound test design and domain knowledge.