Yellow Pages 1996 ad
To avoid the increasing cost of yellow paper, the yellow background of the pages is currently printed on white paper using ink. Yellow paper is no longer used.
The name and concept of “Yellow Pages” came about in 1883, when a printer in Cheyenne, Wyoming working on a regular telephone directory ran out of white paper and used yellow paper instead. In 1886 Reuben H. Donnelley created the first official yellow pages directory, inventing an industry.
Today, the expression Yellow Pages is used globally, in both English-speaking and non-English speaking countries. In the United States, it refers to the category, while in some other countries it is a registered name and therefore a proper noun.
Yellow Pages (YP) are a print directory which provides an alphabetical listing of businesses within a specific geographical area (e.g., Greater Chicago), which are segregated under headings for similar types of businesses (e.g., Plumbers). Traditionally these directories have been published by the local phone company, but due to the highly profitable nature of the business there are numerous independent directory publishers. Some YP publishers focus on a particular demographic (e.g., Christian Yellow Pages or Business Pages).
Yellow Pages directories are usually published annually, and distributed for free to all residences and businesses within a given coverage area. The majority of listings are plain and in small black text, usually in the Bell Gothic or Bell Centennial typefaces. The YP publishers generate profit by selling advertising space or listings under each heading. Advertising may be sold by a direct sales force or by approved agencies (CMR’s). Available advertising space varies among publishers and ranges from bold names up to four color twin page ads (“double trucks”). Advertising rates typically increase every year regardless of distribution or usage fluctuations.
In some countries, the familiar “walking fingers” logo is not protected as a trademark and may be used by anyone. This logo is used in varying forms by almost every YP publisher; however, there are companies that use it to imitate mainstream publishers. In Israel and the Republic of Ireland, the directory, although using the Yellow Pages logo, is called “Golden Pages”.
Info gleaned from Wikipedia