Standard Query Operators for LINQ

Where	Restriction operator based on predicate function
Select/SelectMany	Projection operators based on selector function
Take/Skip/ TakeWhile/SkipWhile	Partitioning operators based on position or predicate function
Join/GroupJoin	Join operators based on key selector functions
Concat
OrderBy/ThenBy/ OrderByDescending/ ThenByDescending	Sorting operators sorting in ascending or descending order based on optional key selector and comparer functions
Reverse	Sorting operator reversing the order of a sequence
GroupBy	Grouping operator based on optional key selector and comparer functions
Distinct	Set operator removing duplicates
Union/Intersect	Set operators returning set union or intersection
Except	Set operator returning set difference
AsEnumerable	Conversion operator to IEnumerable<T>
ToArray/ToList	Conversion operator to array or List<T>
ToDictionary/ToLookup	Conversion operators to Dictionary<K,T> or Lookup<K,T> (multi-dictionary) based on key selector function<
OfType/Cast	Conversion operators to IEnumerable<T> based on filtering by or conversion to type argument
SequenceEqual	Equality operator checking pairwise element equality
First/FirstOrDefault/ Last/LastOrDefault/ Single/SingleOrDefault	Element operators returning initial/final/only element based on optional predicate function
ElementAt/ ElementAtOrDefault	Element operators returning element based on position
DefaultIfEmpty	Element operator replacing empty sequence with default-valued singleton sequence
Range	Generation operator returning numbers in a range
Repeat	Generation operator returning multiple occurrences of a given value
Empty	Generation operator returning an empty sequence
Any/All	Quantifier checking for existential or universal satisfaction of predicate function
Contains	Quantifier checking for presence of a given element
Count/LongCount	Aggregate operators counting elements based on optional predicate function
Sum/Min/Max/Average	Aggregate operators based on optional selector functions
Aggregate	Aggregate operator accumulating multiple values based on accumulation function and optional seed