In 1998, two graduate students at Stanford University, Larry Page and Sergey Brin, developed "Backrub", a search engine that relied on a mathematical algorithm to rate the prominence of web pages. The number calculated by the algorithm, PageRank, is a function of the quantity and strength of inbound links.[22] PageRank estimates the likelihood that a given page will be reached by a web user who randomly surfs the web, and follows links from one page to another. In effect, this means that some links are stronger than others, as a higher PageRank page is more likely to be reached by the random web surfer.
Digital marketing activity is still growing across the world according to the headline global marketing index. A study published in September 2018, found that global outlays on digital marketing tactics are approaching $100 billion.[42] Digital media continues to rapidly grow; while the marketing budgets are expanding, traditional media is declining (World Economics, 2015).[43] Digital media helps brands reach consumers to engage with their product or service in a personalised way. Five areas, which are outlined as current industry practices that are often ineffective are prioritizing clicks, balancing search and display, understanding mobiles, targeting, viewability, brand safety and invalid traffic, and cross-platform measurement (Whiteside, 2016).[44] Why these practices are ineffective and some ways around making these aspects effective are discussed surrounding the following points.
Content is king. It always has been and it always will be. Creating insightful, engaging and unique content should be at the heart of any online marketing strategy. Too often, people simply don't obey this rule. The problem? This takes an extraordinary amount of work. However, anyone that tells you that content isn't important, is not being fully transparent with you. You cannot excel in marketing anything on the internet without having quality content.

Keep resources crawlable. Blocking page resources can give Google an incomplete picture of your website. This often happens when your robots.txt file is blocking access to some or all of your page resources. If Googlebot doesn't have access to a page's resources, such as CSS, JavaScript, or images, we may not detect that it's built to display and work well on a mobile browser. In other words, we may not detect that the page is "mobile-friendly," and therefore not properly serve it to mobile searchers.
Paid search advertising has not been without controversy and the issue of how search engines present advertising on their search result pages has been the target of a series of studies and reports[23][24][25] by Consumer Reports WebWatch. The Federal Trade Commission (FTC) also issued a letter[26] in 2002 about the importance of disclosure of paid advertising on search engines, in response to a complaint from Commercial Alert, a consumer advocacy group with ties to Ralph Nader.
The digital marketer usually focuses on a different key performance indicator (KPI) for each channel so they can properly measure the company's performance across each one. A digital marketer who's in charge of SEO, for example, measures their website's "organic traffic" -- of that traffic coming from website visitors who found a page of the business's website via a Google search.