When we build a C# project in Visual Studio, a file with extension .csproj is created, which lists the contents of the project and configures how it should be built. It's said that a .csproj file has XML format, however, I've been reading the book "Programming C#" by Ian Griffiths which said the format of a project file is "usually" XML. So I'm asking if there is any other formats for project files? If yes what are the formats and where are they used?