Multithreading is a programming technique that allows a computer to perform multiple tasks simultaneously. Instead of running one task at a time, a program can create several threads, which are like mini-programs that can run independently. This helps improve the efficiency and speed of applications, especially when they need to handle many tasks at once, such as in video games or web servers. By using multithreading, developers can make better use of a computer's resources, like its CPU and memory. For example, while one thread is waiting for data from the internet, another thread can continue processing user input, making the application feel faster and more responsive.