Microsoft released latest .Net Framework 4.5 along with the RTM version of Windows 8. If you are using Windows8 you don’t need to install .Net Framework 4.5 in your system because it comes up pre-installed with Windows 8.
By using the .NET Framework 4.5 together with the C# or Visual Basic programming languages, you can write Windows Metro style apps. The .NET Framework 4.5 delivers better performance, reliability, and security. Also there are some core new features and improvements.
Hardware Requirements1 GHz or faster processor 512 MB of RAM 850 MB of available hard disk space (x86) 2 GB of available hard disk space (x64) 350 MB of available hard disk space
In the official Microsoft Download center you will get only Online installer, that means you need to connect to internet till the installation completes. The offline installer is 48MB.Download .net Framework 4.5 Offline Installer. Visit Microsoft .NET Framework Website