هَذَا، هَذِهِ، هَؤُلَاءِ point to persons or things.
هَذَا كِتَابٌ. — This is a book.
Hādhā: demonstrative built on sukūn, in nominative position as subject; kitābun: nominative predicate.
Qualification: certain dual demonstratives (e.g., hādhāni) are declined; not every demonstrative follows one unqualified pattern.