Dating back to the time of primitive man, silver has been referred to by many different naming conventions. The story of how the word "sterling" was incorporated into the name is rooted in 12th-century lore. As payment for English cattle, an association of eastern Germans compensated the British with silver coins dubbed "Easterlings." Eventually, the Easterling was widely accepted as a standard of English currency. The name was ultimately abbreviated to "Sterling," which is now used to refer to the highest grade of silver metal.
The official designation of "sterling" to a piece of silver indicates that it contains at least 92.5% of pure silver. The remaining 7.5% can be comprised of any other metal alloy, most commonly copper. Although it may seem that an even higher silver content would be desirable, that's not actually the case. Metal alloys with a silver content of more than 92.5% are too pliable to be used without suffering from dents and dings. The second alloy is required to ensure the metal's stability and resilience.