From the project home page:
Lightweight NuGet packages with reusable source code extending core .NET functionality, typically in self-contained source files added to your projects as internal classes that can be easily kept up-to-date with NuGet.
Who doesn’t have an ever growing and ever less cohesive miscellaneous collection of helpers, extension methods and utility classes in the usual “Common.dll”? Well, the problem is that there’s really no good place for all that baggage: do we split them by actual behavioral area and create “proper” projects for them?
In most cases, that’s totally overkill and you end up in short time with the same pile of assorted files as you try to avoid setting up an entire new project to contain just a couple cohesive classes....