Smartphone apps account for half of all time spent with digital media, according to comScore's Mobile apps report, and two companies own the overwhelming majority of the most-trafficked apps: Google and Facebook.

Overall, when it comes to time spent on mobile, 87% of mobile time spent is on apps vs. only 13% on mobile web, even though mobile web often receives higher traffic.

Why it matters: Smartphone users spend 96% of their app time within their Top 10 most used apps and Smartphone users spend half their time on their #1 most used app, according to comScore. Google and Facebook own the overwhelming majority of traffic to these apps and are the #1 app for every age group.

• Younger users love apps: Users ages 18-24 spend a whopping 66% of their total media time in mobile apps, or 3.2 hours per day on mobile apps. Younger users are more likely to place YouTube as the top app, instead of Facebook and are much more likely to rank Snapchat as a top app.
• Facebook's app dominance: When it comes to desktop and video traffic, Google is king. But on mobile, Facebook is the clear winner. Facebook maintains its position as the #1 app in monthly users, with 81% penetration among mobile app users. Nearly half (46%) of smartphone users have Facebook on their home screen.

Top apps by category and population penetration in the U.S.:

• Social: Facebook, 93%
• News: Apple News, 77%
• Retail: Amazon, 75%
• Gaming: Words with Friends, 67%
• Travel: Uber, 27%
• Sports: ESPN, 23%
• Dating: Tinder, 11%

Follow the money: in-app advertising has become the one of the fastest-growing mobile ad mediums, with revenue set to surpass $53 billion by 2020. App Annie estimates that by 2020, gross revenue across all app stores will exceed $101 billion globally.