In previous chapters, you’ve seen NuGet package manifests, or .nuspec files, being created a number of times. When creating packages, NuGet uses a convention-over-configuration approach. These conventions are rather simple by default, but relying on them may not be enough to mold the package you wish to create. A NuGet package manifest describes the contents and metadata of your package. It is included in each NuGet package, or .nupkg, file, and it is the file you’ll need to create the actual package. In short, before you can create a package, you’ll need to describe it.