system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: what is the .net framework?
gpt
It's a set of libraries for creating software for Microsoft Windows. It includes standardized ways to represent different types of information, from the simple (such as numbers and text) to the complex (a file on your hard drive, a web address, a database connection). It also includes standardized ways of manipulating this information and interacting with the Windows operating system, such as creating a new file on your desktop, formatting a number according to the user's locale settings, or communicating with a file server.

These are things that a program could in principle do all on its own, but having this common functionality available both saves a tremendous amount of time and effort and helps to keep behavior consistent among different programs. For instance, if a program uses the .Net framework's locale-based number formatting, then it's using the *same* formatting as many other programs and as Windows itself.

The downside is that in order for such a program to run, the computer will have to have the .Net framework installed as well. The .Net framework is periodically updated with new and improved functionality, and newer programs may require a newer version of the framework. Modern versions of Windows should have the latest versions auto-updating, but a lot of older software was written to explicitly make sure that the right version is installed, or even bundled with an installer for that version.