The electromagnetic field differs from aether in that it does not require a medium for propagation, as aether was once thought to do. Aether was hypothesized to be an all-pervasive medium providing a reference frame for electromagnetic waves, whereas electromagnetic fields exist independently of such a medium. There are multiple electromagnetic fields that can be constant or dynamic, complicating the notion of them being at rest or in motion. Unlike aether, which was a singular concept, electromagnetic fields can overlap and interact without a unified medium. Ultimately, the distinction lies in the nature of wave phenomena versus the mediums through which they propagate.