Citations are defined as “mentions” of your business name and address on other webpages, even if there is no link to your website. An example of a citation might be an online yellow pages directory where your business is listed, but not linked to. It can also be a local chamber of commerce, or a local business association where your business information can be found, even if they are not linking at all to your website . Web Reference is also another term for citation.
Citations are a key component of the ranking algorithms of Google, Yahoo & Bing. In most cases if you business has a large number of citations you will probably rank higher than your competition with fewer citations.
Citations from well-established and well-indexed portals (like YP.com for example) help increase the validity that the search engines have about your business’s contact information and categorization.
Citations insures that your business is part of a your community. It’s hard for someone to pretend they are a member of the chamber of commerce or other business affiliations, or have articles in a local online newspaper or local blog. Citations along with links from these kinds of local websites and directories can dramatically improve your Local search engine rankings.
Google + Local has the most citations associated with your business, although not complete.
Here is a list of some of the type of citation building outlets.