wMm

WMM is an acronym that can refer to several concepts in science and technology. In navigation and Earth science the term most often means the World Magnetic Model, while in wireless networking it denotes Wi-Fi Multimedia. Depending on the context, WMM may have other specialized meanings as well.

World Magnetic Model (WMM) is a geophysical representation of the Earth's main magnetic field and its secular variation. It is used to compute magnetic declination, inclination, and total intensity for navigation, surveying, and location-based services. The model is produced jointly by the United States National Oceanic and Atmospheric Administration and the British Geological Survey, with updates issued roughly every five years. WMM provides spherical harmonic coefficients that describe the field over the globe, incorporating recent measurements and the International Geomagnetic Reference Field framework. It underpins compasses in smartphones, aircraft, ships, and many geospatial applications that require magnetic north information.

Wi-Fi Multimedia (WMM) is a quality-of-service feature defined by the Wi-Fi Alliance for IEEE 802.11 networks. It classifies traffic into four access categories—voice, video, best effort, and background—and applies prioritization, admission control, and scheduling to improve performance for real-time and streaming applications. WMM is widely supported by modern routers and client devices, and is often enabled by default to enhance the reliability of VoIP, video conferencing, and online gaming on wireless networks.

In other fields, WMM may refer to organization names or project terms. Context is usually needed to determine the intended meaning.