This article contains a list of download links for the offline/standalone installers for .NET Framework. Each major version is listed, along with the OSes supported by that version.

To install, open the main download for the desired version, select your language, download the main file and run the installer.

For releases that have separate language packs: first download and install the main file. After the installation, click the download link for the language pack, select the preferred language, then download and install that file. You can install more than one language pack on a MUI system.

Version Download links OS requirements .NET Framework 4.6 RC   ...

Microsoft has officially released (some time ago) a tool to download and create your own Windows 8.1 installation media. The tool will request your language, architecture and edition, and how you want to create the media (as an USB stick, or as an ISO file for burning to a DVD). It will then download the necessary files and create your installation media.

The created media will accept all Windows 8.1 OEM, Retail Full, and Retail Upgrade keys. (For Windows 8, see here.)

You can download the tool here: http://windows.microsoft.com/en-us/windows-8/create-reset-refresh-media.