Software developers don’t write all code from scratch. They rely on libraries of code written by other developers. Any modern development platform must provide a mechanism where developers can download and use existing libraries, often called packages. For example, the JavaScript ecosystem has NPM (Node Package Manager), where developers can find and use libraries written by other JavaScript developers.
NuGet is a package manager for the .NET ecosystem. Microsoft developed it to provide access to thousands of packages written by .NET developers. You can also use it to share the code you wrote with others.
A typical web application developed using ASP.NET relies on many open source NuGet packages to function. For example, Newtonsoft.Json is a very popular package (with 91,528,205 downloads at the time of writing) used to work with JSON data in .NET.
