Overview

Classified advertising is usually text-only and can consist of as little as the type of item being sold and a telephone number to call for more information. It can also have much more detail, such as name to contact, address to contact or visit, a detailed description of the product or products ("pants and sweaters, size 10" as opposed to "clothing", "red 1996 Pontiac Grand Prix" as opposed to "automobile"). There are generally no pictures or other graphics within the advertisement, although sometimes a logo may be used.

Classified advertising is called such because it is generally grouped within the publication under headings classifying the product or service being offered (headings such as Accounting, Automobiles, Clothing, Farm Produce, For Sale, For Rent, etc.) and is grouped entirely in a distinct section of the periodical, which makes it distinct from display advertising, which often contains graphics or other art work and which is more typically distributed throughout a publication adjacent to editorial content.

A hybrid of the two forms — classified display advertising — may often be found, in which categorized advertisements with larger amounts of graphical detail can be found among the text listings of a classified advertising section in a publication. Business opportunities often use classifieds to sell their services, usually employing 1-800 numbers. Classified ads are also among the tools used by many companies in recruitment for available job opportunities.

Printed classified ads are typically just a few column lines in length, and they often filled with abbreviations to save space and money.

Developments

In recent years the term "classified advertising" or "classified ads" has expanded from merely the sense of print advertisements in periodicals to include similar types of advertising on computer services, radio, and even television, particularly cable television but occasionally broadcast television as well, with the latter occurring typically very early in the morning hours.

Like most forms of printed media, the classified ad has found its way to the Internet.

Internet classified ads do not typically use per-line pricing models, so they tend to be longer. They are also more readily searchable unlike their offline brethren, tend to be local, and may foster a greater sense of urgency as a result of their daily structure and wider scope for audiences. Because of their self-policing nature and low cost structures, some companies offer free classifieds such as Craigslist, Kijiji and Gumtree internationally. Other companies focus mainly on their local hometown region, while others blanket urban areas by using zip codes. Craigslist.org was one of the first online classified sites, and has grown to become the largest classified source, bringing in over 14 million unique visitors a month according to comScore Media Metrix. A number of online services called Aggregators crawl and aggregate classifieds from sources such as blogs and RSS feeds, as opposed to relying on manually submitted listings.