YouTube mobile ad sales have tripled in just six months, Google (NASDAQ:GOOGL) executives recently told Bloomberg. The growth is another signal that Google's 2006 purchase of YouTube for just $1.65 billion is paying off handsomely.

Even better, as Fool contributor Daniel Sparks explains in the video below, YouTube now accounts for a large enough portion of Google's business to meaningfully contribute to the company's overall growth. In fact, combined with the momentum of growth in digital advertising, YouTube may even boost Google's growth rates in the future.

Fool contributor Daniel Sparks has no position in any stocks mentioned. The Motley Fool recommends Google. The Motley Fool owns shares of Google. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.