An "HD source" refers to a high-definition content source that provides video and audio at a higher resolution than standard definition. This typically includes formats like 1080p or 4K, which offer clearer images and more detailed sound. HD sources can come from various platforms, including Blu-ray discs, streaming services, and cable television. To enjoy the benefits of an HD source, users need compatible devices such as HD televisions or projectors. These devices are designed to display high-definition content, ensuring that viewers experience the best possible quality in their movies, shows, and games.