In addition to being beneficial for search engine optimization and website traffic, directories can also be used to promote businesses that do not have a website. In fact, Internet Yellow Pages are a form of a directory. However, there are directories that cater to a more specific audience, whereas Yellow Pages generally provide business contact information on a large area and a wide variety of industries. Directories that are concentrated on a geographical area but provide listings on a mixture of industries are called geographical or geo-specific directories. Another form of a directory is a vertical or industry-specific directory. These directories have listings of businesses that operate on a specific industry but are not restricted to a small specific regional area. Geo-vertical directories are a mix of the two, concentrating on both specific industry and geographical area. For example, a directory that lists all kinds of businesses in Chicago, Illinois is a geo-specific directory; a directory that lists shoe stores in the United States would be considered a vertical directory; a directory that lists shoe stores in Chicago, Illinois is a geo-vertical directory.
Popular online directories can bring many customers to businesses and the advertising costs involved are usually quite low compared to offline equivalents.