C# v5.0 - Visual Studio 2012
The .NET Framework 4.5 is a direct upgrade to .NET framework 4.0 This means that you cannot have these two versions installed side-by-side When you install .NET 4.5 your .NET 4.0 assemblies in the \Windows\.NET Framework\V4.0.30319 are overwritten with a new set of assemblies
async and await keywords added
Asynchronous methods that you define by using async and await are referred to as async methods.
Caller Information Attributes
This allows you to obtain information about the caller to a method You can obtain the file path, line number and the member name of the caller This is useful when tracing and debugging
Support for arrays that are larger than 2 gigabyte on 64 bit platforms This feature can be enabled in the application configuration file "gcAllowVeryLargeObjects" element
The ability to be able to define a default culture for an application domain
Portable Class Libraries
The Portable Class Library project in Visual Studio 2012 (and later) lets you write and build managed assemblies that work on multiple .NET framework platforms You can choose to target platforms such as Windows Phone and Windows Store
WPF Ribbon Control
Allows you to implement a ribbon user interface that hosts a Quick Access Toolbar, Application Menus and Tabs.
Windows Store Apps
Windows 8.x Store apps are designed for specific form factors and leverage the power of the Windows operating system