Online advertising, also known as online marketing, Internet advertising, digital advertising or web advertising, is a form of marketing and advertising that uses the Internet to promote products and services to audiences and platform users. Online advertising includes email marketing, search engine marketing (SEM), social media marketing, many types of display advertising (including web banner advertising), and mobile advertising. Advertisements are increasingly being delivered via automated software systems operating across multiple websites, media services and platforms, known as programmatic advertising.Like other advertising media, online advertising frequently involves a publisher, who integrates advertisements into its online content, and an advertiser, who provides the advertisements to be displayed on the publisher's content. Other potential participants include advertising agencies that help generate and place the ad copy, an ad server which technologically delivers the ad and tracks statistics, and advertising affiliates who do independent promotional work for the advertiser. In 2016, Internet advertising revenues in the United States surpassed those of cable television and broadcast television.: 14 In 2017, Internet advertising revenues in the United States totaled $83.0 billion, a 14% increase over the $72.50 billion in revenues in 2016. And research estimates for 2019's online advertising spend put it at $125.2 billion in the United States, some $54.8 billion higher than the spend on television ($70.4 billion).Many common online advertising practices are controversial and, as a result, have become increasingly subject to regulation. Many internet users also find online advertising disruptive and have increasingly turned to ad blocking for a variety of reasons. Online ad revenues also may not adequately replace other publishers' revenue streams. Declining ad revenue has led some publishers to place their content behind paywalls.