Advertising revenue represents the monetary income individuals and businesses generate by displaying paid advertisements alongside their internet-based content. This lucrative market was estimated to be worth $111 billion in the U.S. in September 2018, predominantly controlled by tech giants such as Google (under Alphabet Inc.), Facebook, Amazon, and Microsoft.

These platforms also offer significant opportunities for individual content creators; for example, major YouTube personalities like Jake Paul and PewDiePie reportedly earned over $15 million each in 2018 through ad monetization. Google's AdSense is a key platform, allowing websites to display ads and receive 68% of the revenue, which contributes substantially to Alphabet Inc.'s income. However, this online ad revenue is considered taxable in many countries, and the industry faces challenges from the growing use of ad-blocking software by internet users.