The dotnet pack command primarily looks for a .csproj (C# project) file to determine what to package. This file contains the necessary metadata and references for building the project, including information about dependencies, build settings, and output targets.

If you run dotnet pack in a directory that contains multiple .csproj files, it will package each project individually. You can also specify a specific .csproj file to package by providing its path as an argument to the command.