Test-Driven Development (TDD) is a process where tests are written before the code to ensure clean implementation and focus on input/output contract.Advantages of TDD include promoting clean and lean code, thinking through edge cases, and focusing on necessary code.However, TDD can be challenging when clarity is missing and when time pressure or legacy systems are involved.Some developers prefer writing code first and testing later for known problems and efficiency, finding TDD to be a time-consuming process.