There are many people without a citizenship. Some are single cases (people who renounced their relationship but did not get any other relationships), but some are bigger groups, for example:
- the non-Citizens of Latvia - they are mostly Russians who emigrated to Latvia when Latvia was under the Soviet occupation and when Latvia got the independence back, those people had to prove knowledge of Latvian to receive the citizenship - those that didn't, didn't get it.
-Rohingya Muslims in Myanmar - while they have lived there for generations, they were once refugees and never obtained the citizenship.