Cascading is Hibernate's way of using transitive persistence model. Transitive persistence is a technique that allows you to propagate persistence to transient (object not yet saved in database) and detached sub-graphs (child objects) automatically. For example, a newly created child object of already persistent parent object should automatically become persistent without a call to save() or persist() methods.
Cascading in Hibernate has many options like save-update, persist, merge, delete etc. Cascade='all' is a way to apply all cascading options.
