1. Dissolution (► Extinction)
Absorption (► Extinction) (also cession)
Merger
Secession (also self-determination/newly independent State)

2. In case of absorption: "moving-frontiers" principle
Boundary treaties and treaties establishing territorial regimes (erga omnes effect)
Bilateral treaties: presumption of non-succession ("clean slate" principle, except for merger)
Multilateral treaties: accession or declaration/notification of succession (continuity?)
Human Rights treaties: trend towards automatic succession (see also special arrangements for Hong-Kong)
International organisations (except for merger)