So that we can generate PDF documents with the ease that C# gives us for both our desktop and Web applications. With such interesting features as:

• Create PDF documents at runtime with .NET
• Easy compression of the object model for document composition
• Ability to draw on a PDF page, a window or a printer
• Modify, merge or split PDF file
• Images with transparency (color mask, monochrome mask, alpha mask)
• New conception, starting from scratch and written entirely in C#
• Compatibility with .NET graphing classes
• Includes high-level MigraDoc Lite with text layers (you can use both PDFsharp and MigraDoc Lite in a single document)

And lots of examples from here. Like this “Hello World”: