✅ 1. What is JPA?

JPA = Java Persistence API

• It's not a framework, but a specification (a set of rules/interfaces).

• It defines how to map Java objects (classes) to database tables using annotations like:

  
  @Entity, @Column, @Id, @OneToMany, etc.
  
  

🧠 Think of JPA as a contract: it says "Here’s how you should describe an entity and how to query it", but it doesn’t actually run the code.

✅ 2. What is jakarta.persistence (and javax.persistence)?

These are just packages (namespaces), like folders.

💡 They both contain the same JPA API — just moved because Oracle wouldn’t let the Java EE team evolve javax.

So yes — these packages contain the annotations and interfaces you use to define entities and queries.

🧩 They're like the "language" you use to describe how Java maps to SQL.

✅ 3. What is Hibernate?

✅ Hibernate is a real framework — a concrete implementation of JPA.

Hibernate does the actual work:

• It takes your JPA-annotated classes...
• Converts them to SQL commands...
• Executes them on the database...
• Converts SQL result rows back into Java objects in real time.