When I should use one to one relationship?

Question

Sorry for that noob question but is there any real needs to use one-to-one relationship with tables in your database? You can implement all necessary fields inside one table

Answer 1

If data in one table is related to, but does not 'belong' to the entity described by the other, then that's a candidate to keep it separate.

This could provide advantages in future, if the separate data needs to be related to some other entity, also.