With the release of Visual Studio 2010, F# discreetly joined the family of .NET languages fully supported by Microsoft. Like C# or VB, F# is object-oriented and imperative. Unlike them, F# is also a functional language. This makes F# an excellent complement to existing mainstream languages: it interoperates smoothly with them, and handles some problems much better. While not a mainstream .NET language just yet, it has enjoyed a solid adoption in industries such as finance or bioinformatics. Presenting all of F# in one session would be impossible. Instead, our goal will be to give you a general sense for how F# compares to C#. Starting from a tiny C# application (retrieving and analyzing market data from the web), we will convert it step-by-step to F#, illustrating some of the language features that should be particularly interesting for C# developers. We hope that at the end of this excursion, you will understand what F# brings to the table better, and whether it may be a good tool to add to your toolkit!