Spring - @Transactional - What happens in background?

Question

I want to know what actually happens when you annotate a method with @Transactional? Of course, I know that Spring will wrap that method in a Transaction.

Answer 1

All existing answers are correct, but I feel cannot give just this complex topic.

For a comprehensive, practical explanation you might want to have a look at this Spring @Transactional In-Depth guide, which tries its best to cover transaction management in ~4000 simple words, with a lot of code examples.