The Portuguese language, spoken by over 250 million people worldwide, is a rich and complex language with a long history. As with any language, grammar plays a vital role in shaping its structure and ensuring effective communication. In this context, the "Gramática da Língua Portuguesa" by Houaiss is a seminal work that has been widely used as a reference guide for learners, teachers, and linguists alike. This essay aims to discuss the significance of grammar in the Portuguese language, with a focus on Houaiss' comprehensive guide.