Microsoft Dotnet Framework 4.5.1

If you wanted to build a Windows Store App for Windows 8.1, you had to use .NET 4.5.1. You couldn't target 4.5. This "forced upgrade" strategy was Microsoft trying to push the ecosystem forward, but it created headaches for IT departments that were still on Windows 7. While 4.5.1 was deployable on Windows 7, the tight coupling with the controversial Windows 8.1 platform caused some friction in enterprise adoption circles.

Just-In-Time (JIT) compilation utilizes multi-core processors more efficiently to speed up application startup times. microsoft dotnet framework 4.5.1

If you were a developer in 2013 trying to write code that ran on Windows Phone, Windows Store Apps, and the Desktop, you were in pain. If you wanted to build a Windows Store App for Windows 8

: Developers gained the ability to see return values in the debugger for methods that aren't assigned to a variable. While 4

At its launch, .NET 4.5.1 was bundled with and Windows Server 2012 R2 . It was also made available for download on Windows 7 SP1, Windows Vista SP2, and Windows Server 2008/2012. Lifecycle Status

If you are still running on 4.5.1, you are running on an unsupported framework (End of Life: January 2016). Migration to at least 4.6.2 (or ideally .NET 6/8) is critical for security. However, for a nostalgic look back, 4.5.1 was when Microsoft really hit its stride in balancing power with developer productivity.