NS3 is a network simulator that allows researchers and developers to model and analyze the performance of communication networks. It provides a flexible and extensible platform for simulating various network protocols and architectures, making it useful for both academic and industrial applications. The simulator supports a wide range of network technologies, including Wi-Fi, LTE, and 5G. With its user-friendly interface and comprehensive documentation, NS3 enables users to create detailed simulations, visualize results, and test new networking concepts in a controlled environment.