Microsoft Xamarin is a cross platform mobile development framework built on top of Microsoft .NET. Teams can use it to develop for iOS, Android and Windows.
Xamarin comes in two flavours - Native and Forms. Xamarin native creates native apps by wrapping native platform components of iOS and Android. This gives it good performance and flexibility. Xamarin.Forms allows for write-once, run anywhere by adding a layer on top of this.
Xamarine is worth trialing for teams that are already using .NET.