In line with the ever growing popularity of the online world, the digital advertising market has significantly increased in importance over the past years and is now one of the key forms of advertising. In 2015, digital advertising revenues worldwide amounted to about 170 billion U.S. dollars, a figure that is expected to grow to more than 330 billion U.S. dollars by 2021. In a 2017 global comparison, the United Kingdom, Germany and France ranked among the largest online advertising markets in the world, with digital ad revenues of 11.72 billion, 7.37 billion and 5.13 billion U.S. dollars, respectively. Overall, the European online ad market grew by 12.3 percent in 2016 on 2015. The fastest growing online advertising markets that year were Slovenia and Ireland.
In the United Kingdom, digital advertising expenditures increased by nearly five billion British pounds over the eight-year-period between 2007 and 2015, from 2.81 billion British pounds to 7.71 billion British pounds. Paid search and display advertising were the digital ad formats that had the highest share of spending. With regard to digital advertising industry distribution, the travel and FMCG sectors ranked first and second, accounting for 16.8 percent and 16.1 percent of online ad spending in 2015. Keeping in mind the fact that search advertising is one of the major revenue streams for digital advertisers, it comes as no surprise that amongst online companies in the UK, Google's net digital advertising revenue was the highest and was projected to grow further in future years. While Google generated more than 2.5 billion British pounds in revenue through its digital advertising channels in 2013, Facebook’s digital ad revenue accounted for 371 million British pounds.
Meanwhile, ad blocking services and their increasing popularity are having a significant effect on the revenues of the digital advertising market. In 2015, it was estimated that revenue losses due to the use of ad blockers amounted to 3.6 billion U.S. dollars in the UK. In 2016, Western Europe had the highest penetration of enabled ad blocking software in the world. France and Germany were the leading European countries in terms of ad blocking use in 2015, at 27 percent and 24 percent, respectively.