SOLID is an acronym for five principles of architecture.

S – Single Responsibility Principle. It states that every class should have single responsibility. A class should not have more than one reason to change.

O – Open Close Principle. A class should be open for an extension and closed for the modification.

L – Liskov Substitution Principle . A parent object should be able to replace its child during runtime polymorphism.

I –Interface Segregation Principle. Client specific interfaces are better than general purpose interfaces.

D – Dependency Inversion Principle. Clients should not be forced to depend upon interfaces that they do not use

Ref: https://www.slideshare.net/kumareshbaruri/solid-principles-251298958