TEST-NET is a simulated environment used for testing and developing applications without the risks associated with real-world transactions. It allows developers to experiment with their code, ensuring everything works correctly before launching it on the main network. This is especially important in fields like cryptocurrency, where mistakes can lead to significant financial losses. In the context of blockchain technology, TEST-NET provides a platform for developers to interact with smart contracts and decentralized applications in a safe space. By using TEST-NET, developers can identify bugs and improve their projects, ultimately leading to more reliable and secure applications for users on the main network.