Hi-Fis are high-fidelity sound systems, often referred to as stereos. They are designed to reproduce sound with a greater level of accuracy and clarity than standard audio systems. Hi-Fis typically include components such as amplifiers, speakers, and turntables. They are used for listening to music, watching movies, and playing video games. Hi-Fis are popular among audiophiles and music enthusiasts who want to experience the highest quality sound possible.