S
Single responsibility principle
O
Open/Close Principal
L
Liskov substitution principle
I
Interface segregation principle
D
Dependency inversion principle
Single responsibility principle
A class should have only a single responsibility
Open/Close Principal
Software entities should be open for extension, but closed for modification.
Liskov substitution principle
objects in a program should be replaceable with instances of their subtypes without altering the correctness of that program.
Interface segregation principle
Many client-specific interfaces are better than one general-purpose interface.
Dependency inversion principle
One should depend upon abstractions, not concretions.