The yellow pages are any telephone directory of businesses, organized by category rather than alphabetically by business name, and in which advertising is sold. The directories were originally printed on yellow paper, as opposed to white pages for non-commercial listings. The traditional term "yellow pages" is now also applied to online directories of businesses.
In many countries, including Canada, the United Kingdom, Australia, and elsewhere, "Yellow Pages" (or any applicable local translations), as well as the "Walking Fingers" logo first introduced in the 1970s by the Bell System-era AT&T, are registered trademarks, though the owner varies from country to country, usually being held by the main national telephone company (or a subsidiary or spinoff thereof). However, in the United States, neither the name nor the logo was registered as trademarks by AT&T, and are freely used by several publishers. This can sometimes be very confusing as YP (AT&T) and yellow pages are similar in nature.