What is denormalization and when would you go for it

As the name indicates, denormalization is the reverse process of
normalization. It's the controlled introduction of redundancy in to
the database design. It helps improve the query performance as the
number of joins could be reduced.

What is Normalization

A relational database is basically composed of tables that contain related data. So the Process of organizing this data into tables is actually referred to as normalization.