What is the difference between @Transactional propagation types in Spring?

Propagation defines how transactions behave when a method calls another transactional method.

Spring provides propagation levels like REQUIRED, REQUIRES_NEW, NESTED, SUPPORTS, NOT_SUPPORTED, MANDATORY, and NEVER. REQUIRED joins existing transaction or creates a new one. REQUIRES_NEW suspends current transaction and creates a new independent one. These control atomicity boundaries in complex service orchestration.