Digital advertising spending has been on a strong growth trajectory since its inception. The Interactive Advertising Bureau’s report on the first half of 2019 had revenue totaling $57.9 billion, which represented a 16.9% increase from the same period in 2018. But in the numbers was one important sign of maturity of the industry. It’s the first time that revenues for the first half of a year were lower (by $30 million) than the second half of the previous year.