To identify pottery and ceramic marks, conduct online image searches on the logos or use a resource such as Kovel's New Dictionary of Marks. Make note of any aspect of the mark, such as an image, country name, specific wording or whether the mark has "LTD" stamped on it.
Some companies maintained the same markings for decades or centuries, making identification easy with a simple search. More complex marks can be identified by enlisting the help of a service that researches antique or obscure artwork, like Kovel. Many times, these pieces are Europe, with an occasional piece coming from an Asian country. From 1891, the United States required any item entering the country to be marked with a "Made in" stamp. Pieces marked "Made in Nippon" or "Nippon" are Japanese in origin and date before 1921.
Pottery marks can identify the maker of a piece, its age and place of manufacture. Some pieces include logos or initials identifying the artist who created that particular design. For example, the Wedgewood company in England used a kite symbol with the mark "Rd" that identifies those pieces as made from 1842-1883, while marks stamped in any color except blue identify the piece as made after 1850. Most company's marks are distinct and easy to identify.