There are several different types of silver that you may come across while jewelry. Learning the differences will allow you make an educated purchase with regard to price and quality.
Sterling Silver. As a naturally soft metal, pure silver must be mixed with other metals in order to be malleable and durable for jewelrymaking. It is often mixed with copper to create an alloy (mixture of two or more metals) resulting in what we commonly know as sterling silver. While copper makes silver harder, it also gives it a tendency to tarnish. Sterling silver does require maitenence and cleaning, which luckily can be minimized with efficient anti-tarnish protection. In order to be considered sterling, the alloy must contain at least 92.5% pure silver. Sterling jewelry will be marked with 92.5, 925, or Ster so keep an eye out when shopping!
Pure Silver. Containing 99.9% silver, pure silver is extremely soft, too soft to maintain any shape as in jewelrymaking. It bends, breaks and stretches too easily. The point of knowing this fact is more for the purpose of identifying fake or knockoff jewelry items. If someone is advertising "100% silver" or making similar claims, you know this is not possible.
Silver Plate. Silver plated jewelry is produced by covering the base metal with a thin outer layer of silver. Silver plated jewelry is usually made for the lower-end, low quality market as this silver coating will eventually wear away revealing the base metal underneath. In theory, the thicker the silver coating, the longer the life of your silver plated jewelry. So when buying this type of jewelry, try to get an idea of the silver plate thickness.
Now you're ready to get shopping and make your silver jewelry purchase!