In this chapter we learned about LINQ, Microsoft’s query technology for querying collections, relational databases, and XML files (along with community implementations for many other queryable things). We saw how to use both query and method syntax provided by LINQ to perform common query operations. Finally, we examined the mechanism LINQ uses to provide new functionality to IEnumerable collections - extension methods. We even implemented a few extension methods of our own!

Now you should be ready to use LINQ in your own projects, as well as define your own custom extension methods.