Skyboxes have many names: HDRI's, World Environments, and Equirectangular Maps. They all do the same thing: Fill a 3D space with an infinite source of sky texture and world-based lighting.
Skyboxes are often the unsung hero of all 3D worlds, from video games to rendered animations to VR/AR. It's common to utilize free HDRI's from places like Polyhaven.com. These are convenient but limited.
Did you know you can create custom skyboxes with Blender? With custom skyboxes you can create any mood, time of day, and output whatever resolution you need!