In the world there are round 10 million peoples without any citizenship. i need information about them because i need it for a project. who are this peoples? where do they leave? ( in which lands, with details ) why they are without any citizenship?do not answer if you don't have information.

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. 

D. providing for public safety