CRUD represents Create, Read, Update, and Delete. It is important because it defines the basic operations required for data management in applications and ensures a structured way of interacting with databases and APIs.

• Create → INSERT INTO table_name ...
• Read → SELECT * FROM table_name ...
• Update → UPDATE table_name SET ...
• Delete → DELETE FROM table_name ...

CRUD maps to HTTP methods:

• Create → POST
• Read → GET
• Update → PUT or PATCH
• Delete → DELETE

Common challenges include performance issues, data integrity, and concurrency conflicts. Optimizations involve using indexes, proper query design, transactions, caching, and implementing access control.

ORMs abstract CRUD operations into methods. For example, in Hibernate, session.save() performs Create, session.get() performs Read, session.update() performs Update, and session.delete() performs Delete. This makes database operations easier without writing raw SQL.