Microsoft makes a lot of apps for multiple platforms. It also makes a lot of tools that are used by other developers to build apps for multiple platforms. It only makes sense then that the company would be interested in buying Xamarin, one of the leading platform providers for mobile app development.
While you may not have heard of Xamarin, its solution counts as one of the invisible threads that play a role in running the Internet nowadays. The platform helps developers use a shared codebase in C# to build, test, and monitor native apps for iOS, Android, and Windows, all with the same IDE, language, and APIs. It essentially makes life a lot easier for them so they can accelerate development and deployment across platforms.
Even though it's only 4 years old, Xamarin counts over 350 employees and over 15,000 customers (100 of which are Fortune 500 companies) in 120 countries. One of its partnerships was with Microsoft, where it integrated its solution in Visual Studio, Microsoft Azure, Office 365, and the Enterprise Mobility Suite. Now that partnership is moving to the next level thanks to this acquisition.
No price was disclosed, but both Microsoft and Xamarin seemed pretty happy and hopeful about the future in their respective blog posts. They'll be revealing more of their plans at Microsoft's Build conference in March and Xamarin Evolve in April.