(Note: A lot of answers discuss LINQ to SQL, which ZLinq does not appear to optimize.) Iterators: LINQ works on any type that supports iterators. In most langu

(Note: A lot of answers discuss LINQ to SQL, which ZLinq does not appear to optimize.) Iterators: LINQ works on any type that supports iterators. In most languages, this is any type that you can write a for (foreach) loop on and perform an operation on each item in a collection / array / list. (In C#, the collection must implement the IEnumerable<T> interface.) Lambda functions: LINQ then relies heavily on Lambda functions, which are used as filters or to transform / narrow down data. Most languages also have something similar to these. Generics: C# allows for "list of foo objects" instead of "list of objects that I have to typecast to foo." Although not explicitly required to implement something LINQ-like in other languages, the compiler verifying type helps with autocomplete and in-IDE suggestions; and helps avoid silly typing bugs. Generic inference: C# can infer the return type from a lambda function, and infer the argument type in a lambda function. This means you don't need to decorate LINQ syntax with type information; except in some rare corner cases. This is why, for example, there are LINQ-like libraries in Javascript and Rust. Java supports something that is LINQ-like, although in my limited Java experience, I didn't use it enough to really "get the hang" of it. --- Note that LINQ has a very serious pitfall: It's easy to accidentally build a filter, and then have a lot of overhead re-running an expensive operation to re-load the source collection. The simplest way to avoid this is to call .ToArray() or .ToList() at the end of the chain to ensure that you store the result in a collection once.