Drupal by default create 63 tables.

1. node ( In this table store list of content types available like Article, Page etc… )
2. users_field_data ( In this table store user details like name, password, mail etc… )
3. user__roles (In this table store user roles based on user id)
4. node_field_data ( In this table store list of articles, pages etc… )
5. comment_field_data ( In this table store comments with their description )