Online advertising, also called online marketing or Internet advertising or web advertising, is a form of marketing and advertising which uses the Internet to deliver promotional marketing messages to consumers. Consumers view online advertising as an unwanted distraction with few benefits and have increasingly turned to ad blocking for a variety of reasons.
It includes email marketing, search engine marketing (SEM), social media marketing, many types of display advertising (including web banner advertising), and mobile advertising. Like other advertising media, online advertising frequently involves both 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 who 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 2011, Internet advertising revenues in the United States surpassed those of cable television and nearly exceeded those of broadcast television.:19 In 2013, Internet advertising revenues in the United States totaled $42.8 billion, a 17% increase over the $36.57 billion in revenues in 2012.:4–5 U.S. internet ad revenue hit a historic high of $20.1 billion for the first half of 2013, up 18% over the same period in 2012. Online advertising is widely used across virtually all industry sectors.:16
Many common online advertising practices are controversial and increasingly subject to regulation. Online ad revenues may not adequately replace other publishers’ revenue streams. Declining ad revenue has led some publishers to hide their content behind .
In early days of the Internet, online advertising was mostly prohibited. For example, two of the predecessor networks to the Internet, ARPANET and NSFNet, had “acceptable use policies” that banned network “use for commercial activities by for-profit institutions”. The NSFNet began phasing out its commercial use ban in 1991
Email marketing is sending a commercial message, typically to a group of people, using email. In its broadest sense, every email sent to a potential or current customer could be considered email marketing. It usually involves using email to send advertisements, request business, or solicit sales or donations, and is meant to build loyalty, trust, or brand awareness. Email marketing can be done to either sold lists or a current customer database. Broadly, the term is usually used to refer to sending email messages with the purpose of enhancing the relationship of a merchant with its current or previous customers, to encourage customer loyalty and repeat business, acquiring new customers or convincing current customers to purchase something immediately, and adding ads to email messages sent by other companies to their customers.
Email marketing has evolved rapidly alongside the technological growth that has occurred throughout the 21st century. Prior to this growth, email marketing was not as effective because of a lack of reach, as emails were novelties to the majority of customers and potential customers. In 1978, Gary Thuerk of Digital Equipment Corporation (DEC) sent out the first mass email  to approximately 400 potential clients via the Advanced Research Projects Agency Network (ARPANET). It resulted in $13 million worth of sales in DEC products, and highlighted the potential of marketing through mass emails. As email marketing developed itself as an effective means of direct communication, a problem arose in that users were blocking out large amounts of content from emails by use of filters and blocking programs. It therefore became the case that in order to effectively communicate a message through email, marketers had to develop a way of pushing content through to the end user, without being cut out by automatic filters and spam removing software. This resulted in the birth of triggered marketing emails, which are sent to specific users based on their tracked online browsing patterns.
Historically, it has been difficult to measure the effectiveness of marketing campaigns because it is not always possible to fathom what portion of a target market has been reached. Email marketing carries the benefit of allowing marketers to immediately identify returns to investment and therefore measure and improve efficiency. Email marketing allows marketers to see feedback from users in real time, and to monitor how effective their campaign is in achieving market penetration and helps to reveals how wide or narrow a communication channel is. At the same time however, it also means that the more personal nature of certain advertising methods, such as television advertisements, cannot be captured.