FACTBOX: DoubleClick a leader in its field

BRUSSELS (Reuters) - The European Commission on Tuesday approved plans by Google to purchase DoubleClick for $3.1 billion. Here is background on DoubleClick:

-- Specialises in corporate brand marketing in contrast to Google's delivery of ads alongside Web search. Google ads are simple text-based direct marketing ads.

-- Most successful dot-com company to emerge out of Madison Avenue during the mid-1990s.

-- The largest independent supplier of graphical ads such as online banners that major advertisers prefer for online corporate brand marketing campaigns.

-- Provides advertising technology allowing Web site publishers, advertisers and ad agencies to serve brand advertising to Web users. It delivers ads to mobile phone callers and electronic billboards.

-- Focuses on technology connecting buyers and sellers of online advertising, while its customers buy online ads, create ad packages or own online ad space.

-- Has 14 data centres worldwide managing online ad traffic for its customers, both graphical and video.

-- Functions behind the scenes, so is little known to consumers who see its ads daily on the Web.

-- Since April 2007, has run an advertising exchange to connect online ad buyers and sellers. Hundreds of ad networks exist including companies such as Advertising.com, a unit of Time Warner's AOL division and ValueClick.

-- Run DART online since 1997 allowing advertisers, Web site publishers and ad agencies to deliver, target, measure and report the effectiveness of ads delivered over its software.

-- Market research firm Kelsey Group recently forecast the online advertising market to generate revenue of $147 billion worldwide in 2012, triple that in 2007 and far faster than other kinds of advertising.

(Editing by David Lawsky and David Hulmes)

(Reporting by Eric Auchard)