Test-Driven Development (TDD) is a software development practice in which developers write automated tests before writing the actual code. The process follows a simple cycle: first, the developer writes a failing test case for a new feature or function; next, they write the minimum amount of code necessary to pass the test; finally, they refactor the code to improve its structure and remove any redundancies. This cycle is repeated continuously, with each new test driving the development of the codebase.

TDD offers several benefits, including higher code quality, fewer bugs, and better-designed software. By writing tests first, developers ensure that their code is testable and meets the specified requirements. It also encourages a modular, decoupled design, making the code easier to maintain and extend over time. TDD is often used in conjunction with Agile methodologies, where it supports continuous integration and delivery practices. However, TDD requires discipline and can be time-consuming, particularly for complex systems. Despite these challenges, TDD is widely regarded as a best practice for producing reliable, high-quality software.