Design Principles

SOLID Principles:
SRP:(single responsibility principle)
OCP:(Open Close Principle)
LSP: (Liskov substitution principle - Design By Contract)
ISP:(Interface-segregation principle)
DIP:(Dependency inversion principle)

Inheritance --> is - a
Composition --> part - of
Aggregation --> has - a

LINQ

Aggregate	Conversion	Ordering	Partitioning	Sets
Aggregate	Cast	OrderBy	Skip	Concat
Average	OfType	ThenBy	SkipWhile	Distinct
Count	ToArray	Descending	Take	Except
Max	ToDictionary	Reverse	TakeWhile	Intersect
Min	ToList			Union
Sum	ToLookup
	ToSequence