Denomalization on the contrary is the process of adding redundant data to speed up complex queries involving multiple table JOINS. One might just go to a lower form of Normalization to achieve Denormalization and better performance. Data is included in one table from another in order to eliminate the second table which reduces the number of JOINS in a query and thus achieves performance

Normalization Pros:
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no (or at least reduced) redundancy
faster writes if just 1 smaller table needs updating/inserting/deleting
ideal for transaction (OLTP) systems

Denormalization Pros:
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easier for nontechnical users to understand
faster reads if all or most of the data is needed anyway
ideal for reporting (OLAP) systems