Most pottery has a maker's mark located on the bottom that can be cross referenced with known studio marks. Marks are identified by comparing the stamp with photos of studio marks.
Pottery companies mark their works with full names, initials or symbols. Marks are stamped, embossed, etched, sometimes only a piece of paper on the bottom of the piece.
The simplest marks to identify are the studios that spell out the company name on the mark. These marks have the entire name of the company stamped into the piece and occasionally list extra information such as artist initials and dates.
Some studios used initials to identify their pieces. These marks are more difficult to identify if you do not know each studio's marks. Online resources such as The Marks Project feature images of different studio marks for identifying companies by initials.
Symbols are another way that studios marked their works. Marks such as sailboats or sunbursts are created by studios to identify their pieces. In addition to the symbol, some studios have artist initials, dates or location initials stamped with the mark. To identify studio marks, consumers need to learn the symbols each studio used.
While most pottery is marked, there are significant pieces that have no markings that experts are able to identify. A piece that appears antique but does not have a mark is most likely a modern reproduction.