Great job — we just covered a lot of LINQ! Here’s a recap:

• LINQ is a set of language and framework features for writing structured, type-safe queries over local object collections and remote data sources.
• Use LINQ by referencing the System.Linq namespace in your file.
• When a LINQ query returns a sequence of elements its type is IEnumerable<T>. That means it works with foreach loops and its length is accessible with Count().
• Store a query’s result in a variable of type var. var is an implicit type, meaning it gets all of the benefits of type-checking without our specifying the actual type.
• LINQ queries can be written in method syntax or query syntax.
• We prefer method syntax for single operations and query syntax for most everything else.
• The Where operator is used to select certain elements from a sequence.
• The Select operator determines what is returned for each element in the sequence.
• The from operator declares a range variable that is used to traverse the sequence.
• LINQ can be used on arrays and lists, among other datatypes.

If you’re curious or want more practice, here are some additional resources:

• Learn more by reading Microsoft’s guide to LINQ.
• Find a list of keywords for query syntax here.
• Find a list of common methods for method syntax here.
• Find a complete list of methods for IEnumerable<T> here.