What is Option in Scala and how does it replace null?

Option[T] is Scala's type-safe alternative to null references. It is a container with two subtypes: Some(value): contains a non-null value. None: represents the absence of a value. Instead of returning null (which causes NullPointerException), functions return Option: def findUser(id: Int): Option[User]. Working with Options: pattern match: opt match { case Some(v) => use(v); case None => default }. getOrElse: opt.getOrElse("default"). map: transform if present: opt.map(_.name). flatMap: chain optional operations. foreach: execute side effect if present. filter: convert Some to None if condition fails. Option makes the possibility of absence explicit in the type signature, forcing callers to handle both cases at compile time.