The word metadata shares the same Greek root as the word metamorphosis. Metadata can help the city planner, the graduate student in geography, or the forest manager find and use geospatial data, but they also benefit the primary creator of the data by maintaining the value of the data and assuring their continued use over a span of years. The concept of metadata is familiar to most people who deal with spatial issues. A map legend is pure metadata. The legend contains information about the publisher of the map, the publication date, the type of map, a description of the map, spatial references, the map's scale and its accuracy, among many other things.
Metadata are simply that type of descriptive information applied to a digital geospatial file.
They're a common set of terms and definitions to use when documenting geospatial data. Most digital geospatial files now have some associated metadata. Metadata helps people who use geospatial data find the data they need and determine how best to use it. Metadata benefit the data producing organization as well. As personnel change in an organization, undocumented data may lose their value.