What are case classes in Scala?

Case classes in Scala are special classes optimized for immutable data modeling. Declaring case class Person(name: String, age: Int) automatically provides: Immutable fields accessible as person.name. toString: Person(Alice, 30). equals and hashCode: structural equality based on fields (not reference). copy(): create a modified copy: person.copy(age = 31). Companion object with apply: create without new: val p = Person("Alice", 30). Pattern matching support: p match { case Person(n, a) => println(n) }. Serializable by default. Case classes are the idiomatic way to represent domain objects, ADT (Algebraic Data Type) variants, and message types in Akka in Scala.