Personal pronouns in Portuguese are divided into subjects, direct and indirect objects, forms of address, and reflexive pronouns. Each category has specific functions in a sentence and can have different forms. Subject pronouns indicate who performs the action, while object pronouns receive or complete the action of the verb. Reflexive pronouns indicate that the subject both performs and receives the action. Forms of address substitute "you" or "tu" in formal situations and vary according to the degree of formality.

The personal pronouns in the nominative case are I, you (tu), you (você), he, she, we, you all (vós), you all (vocês), they (masc. or mixed) and they (feminine). They function as the subject of the verb and determine verbal agreement. "Tu" and "vós" are more common in certain regions, while "you" and "you all" are widely used in everyday speech. "He" and "she" can also substitute nouns already mentioned to avoid repetition.

The personal pronouns in the oblique case are used as direct or indirect objects and vary in unstressed (clitic) and stressed forms. Unstressed forms appear attached to the verb through proclisis, enclisis, or mesoclisis and are common in formal writing. Stressed forms usually come with a preposition and are used to avoid ambiguity or for emphasis. The choice between unstressed and stressed forms depends on the syntactic function and the sentence structure.

Reflexive pronouns indicate that the subject is also the target of the verb's action and agree with person and number. The most common forms are me, te, se, nos, and vos, which can appear before or after the verb depending on the sentence order. In Portuguese, the reflexive can be obligatory with certain verbs and can change the verb's meaning. "Se" also appears in constructions of synthetic passive voice and indeterminate meaning.

Forms of address are used to express respect or formality and usually require third-person agreement. The most common forms are "you" in everyday language and "Mr." or "Ma'am" in formal contexts. Other forms appear in specific situations, such as with authorities or in official written language. Appropriate use depends on the social context and the relationship between the interlocutors.

Subject pronouns determine the form of the verb by person and number. With "you" and "you all", the verb agrees in the third person, even though the addressee is the subject. "I" and "we" require first person singular and plural, respectively. In formal registers with forms of address, the agreement remains in the third person.

The placement of unstressed pronouns can be by proclisis, enclisis or mesoclisis, depending on the elements that attract or position the pronoun. Proclisis occurs with negations, relative pronouns, subordinate clauses and certain adverbs. Enclisis is preferred at the beginning of sentences in formal written Portuguese and after the verb in the infinitive or gerund. Mesoclisis appears with the future tense in formal constructions. In speech, proclisis is the predominant order, especially with "me", "te", "se" and "nos".

The use of "tu" and "vós" varies by region, as does the preference for certain object forms. In many regions, "you" (você) replaces "tu" in conversation, but it can coexist with "tu" in hybrid systems. The choice between "lhe" and constructions with "para + pronoun" can also vary in speech. Knowledge of variation helps interpret and adapt language in different contexts.

Personal pronouns organize who is speaking, with whom one speaks and about whom one speaks, in addition to regulating agreement and placement. Mastery of the forms of the subject, objects, and reflexives enables you to construct clear and correct sentences. Using appropriate forms of address and paying attention to regional variation increases the effectiveness of communication in Portuguese.