Hello.
Citizenship is basically a legal stage which used to given to a person under the  limit of a particular state where he/she actually born.
There are several type of citizenship some of these are mentioned below you can consider these as a type  as well as method to obtain citizenship.

• By domicile
• By migration.
• By registration.
• By decent.
• By birth.
• By naturalization, etc.

Best of luck.