Because users have different operating systems, web browsers and computer hardware (including mobile devices and different screen sizes), online ads may appear to users differently from how the advertiser intended, or the ads may not display properly at all. A 2012 comScore study revealed that, on average, 31% of ads were not "in-view" when rendered, meaning they never had an opportunity to be seen. Rich media ads create even greater compatibility problems, as some developers may use competing (and exclusive) software to render the ads (see e.g. Comparison of HTML 5 and Flash).
Studies have shown that success with referral campaign is 2% but is much better than direct mail campaigns which have a success rate of only 1%. Some marketers feel asking for a referral could damage the relationship with the customer. Companies that are not willing to seek referrals can take the indirect route by establishing their expertise through better visibility in websites, blogs, podcasts, YouTube, appearing on TV among other options. This, in turn, may help the company get references from people who aren’t its customers.
"One client was very happy with his rankings so he sent the entire team to Atlantic City, all expenses paid. Then he said, 'I loved hearing that you all enjoyed the trip. It's great giving back the joy that I get from seeing us going up in rank. I am hoping to present more such rewards for the remarkable job you are continuing to do, and for Jim's brilliant leadership.'" Rafael D.
In the case of cost per mille/click, the publisher is not concerned about whether a visitor is a member of the audience that the advertiser tries to attract and is able to convert, because at this point the publisher has already earned his commission. This leaves the greater, and, in case of cost per mille, the full risk and loss (if the visitor cannot be converted) to the advertiser.
The introduction of social media has caused a change how viral marketing is used and the speed at which information is spread and users interact. This has prompted many companies to use social media as a way to market themselves and their products, with Elsamari Botha and Mignon Reyneke stating that viral messages are "playing an increasingly important role in influencing and shifting public opinion on corporate reputations, brands, and products as well as political parties and public personalities to name but a few."
According to the U.S. Commerce Department, consumers spent $453.46 billion on the web for retail purchases in 2017, a 16.0% increase compared with $390.99 billion in 2016. That’s the highest growth rate since 2011, when online sales grew 17.5% over 2010. Forrester predicts that online sales will account for 17% of all US retail sales by 2022. And digital advertising is also growing strongly; According to Strategy Analytics, in 2017 digital advertising was up 12%, accounting for approximately 38% of overall spending on advertising, or $207.44 billion.