.NET Framework 4.5 comes installed with Windows 8. If you are using Windows 8, you will have version 4.5 installed. You can download the latest version from below and install it in Windows 8. System requirements for .NET Framework 4.5.1 includes the following: A minimum free space of 850 MB for 32-bit Windows and 2 GB for 64-bit Windows is required for installation. Supported Operating Systems include Windows 8, Windows 7 SP1, Windows Vista SP2 and Windows Server 2008 R2. There are two types of installers available for .NET Framework 4.5.1 installation. The web installer will download the components during installation while the offline installer will download the complete installation which doesn’t need to connect to the Internet for further installation. According to Microsoft: Some known issues with .NET Framework 4.5.1 are given in KB2890857. New features of the .NET Framework include:

Performance and reliability improvementsAbility to suspend and resume operations in the ASP.NET page frameworkAbility to compact large object heaps on-demand64-bit Edit and Continue controlsAbility to trace and sample activitiesImprovements that make SQL connections more resilientAbility to manage return values

Installing .NET Framework 4.5.1 is quite easy. Just download and save the installer from the link below and run the setup file. If you want to deploy it to multiple computers, you may want to read about .NET Framework 4.5.1 command line switches for silent installs. Download .NET Framework 4.5.1 offline installer (English + All languages) Download .NET Framework 4.5.1 offline installer (French) Download .NET Framework 4.5.1 offline installer (German) Download .NET Framework 4.5.1 offline installer (Arabic) Download .NET Framework 4.5.1 offline installer (Italian) Download .NET Framework 4.5.1 offline installer (Japanese) Download .NET Framework 4.5.1 offline installer (Russian) Download .NET Framework 4.5.1 offline installer (Spanish) Download .NET Framework 4.5.1 offline installer (Swedish) Download .NET Framework 4.5.1 offline installer (Turkish)