The purpose of a test-driven development (TDD) approach is to improve software quality by ensuring that tests are written before the actual code. This methodology emphasizes the creation of automated tests for each feature or module, which developers strive to pass during coding. TDD leads to a more structured development process and encourages simpler design choices, promoting better code organization and reducing defects. By integrating testing early in the development cycle, TDD helps ensure that features function correctly and meet requirements, ultimately increasing reliability and maintainability of the software.