Some ways to identify the stamp marks on silver include taking the piece to an expert appraiser or looking at an online or printed encyclopedia of marks. These marks are called "hallmarks," or sometimes "maker's marks," and convey a good deal of information about the piece.
According to "Modern Silver" magazine, a hallmark and a maker's mark are not the same thing, although the two are often conflated by non-experts. A hallmark is an indication of the metal content of a piece, signifying the purity and quality of the metal. Hallmarks may also contain maker's marks, which are a kind of trademark left by the craftsman who made the piece. In addition to metal quality, hallmarks sometimes lend clues to the geographic and temporal origin of the piece. Hallmark systems have varied throughout human history, coming into existence at least as far back as the 4th century in the Byzantine Empire, and have continued to this day, with different countries utilizing different hallmark systems.
Many experts can identify various common hallmarks from memory, making the process of identification much easier. However, there are online guides, such as Modern Silver's "Basic Hallmarks Identification Guide," and the "Online Encyclopedia of Silver Marks, Hallmarks, and Maker's Marks," that offer a novice collector help in identifying pieces.