Coordinating conjunctions link terms or clauses of the same syntactic function and organize the logical relation between ideas without creating dependency between them. They can add, oppose, alternate, conclude or explain what was said before. In more formal uses, forms such as however, nevertheless and nonetheless are preferred, while in colloquial language it is also common to begin sentences with conjunctions.

Additive conjunctions add information and show continuity between ideas. The most frequent are and, nor and in addition, and the general sense is of addition or accumulation. When the clause is already negative, nor reinforces the negation and tends to appear naturally in pairs like Subordinating Conjunctions in more complex structures.

IdeiaIdea	ExemploExample
A conjunção e acrescenta uma ideia à outra.The conjunction 'and' adds an idea to another.	Estudou e passou.Studied and passed.
A conjunção nem soma uma negação a outra negação.The conjunction 'nor' adds a negation to another negation.	Não vi nem ouvi.I neither saw nor heard.
Além disso introduz uma informação adicional.Additionally introduces an extra piece of information.	Falou bem, além disso escreveu com clareza.He spoke well; in addition, he wrote clearly.

Adversative conjunctions oppose two ideas and mark contrast, restriction or break of expectation. The most common forms are but, however, nonetheless and nevertheless, with a formal register more common in the last three. The comma is usually placed before these conjunctions, because they tend to open a relation of opposition between clauses.

IdeiaIdea	ExemploExample
Mas introduz oposição entre duas ideias.But introduces opposition between two ideas.	Queria ir, mas choveu.I wanted to go, but it rained.
Porém mantém contraste com tom mais formal.However maintains contrast with a more formal tone.	Estava cansado, porém continuou.He was tired, however he continued.
Contudo e todavia reforçam oposição em registro formal.Nonetheless and nevertheless reinforce opposition in a formal register.	Pediu silêncio, contudo houve ruído.He asked for silence, nonetheless there was noise.

The alternative conjunctions present choice, alternation or possibility between terms and clauses. The most frequent forms are or, either... or and whether... or, which distribute the options symmetrically. In varied texts, Disjunctive Conjunctions also appear in repetition constructions that emphasize alternation.

IdeiaIdea	ExemploExample
Ou apresenta uma escolha entre duas possibilidades.Or presents a choice between two possibilities.	Ou estuda, ou falha.Or studies, or fails.
Ora...ora alterna situações ou ações.Either... or alternates situations or actions.	Ora chove, ora faz sol.Either it rains, or it is sunny.
Quer...quer indica alternativa válida em qualquer caso.Whether... or indicates a valid alternative in any case.	Quer venha, quer não venha, haverá encontro.Whether he comes or not, there will be a meeting.

The concluding conjunctions indicate consequence, conclusion or inference drawn from what was said before. Therefore and for that reason are the most frequent forms and tend to appear after information that serves as a base for the conclusion. In argumentative structures, they approach reasoning marks used with Conclusive Conjunctions.

IdeiaIdea	ExemploExample
Logo introduz uma conclusão direta.It directly introduces a conclusion.	Pensou bastante, logo decidiu.He thought a lot, thus he decided.
Portanto apresenta consequência ou dedução.Therefore it presents consequence or deduction.	Choveu, portanto cancelaram.It rained, therefore they canceled.
Por isso explica o resultado de algo anterior.For this reason explains the result of something earlier.	Acordou tarde, por isso se atrasou.He woke up late, hence he was late.

Explanatory conjunctions justify the preceding statement and present a cause, explanation or clarification. Pois, with explanatory value, and isto é are central forms of this group, but they do not always substitute for the causality of other structures. When the explanation comes after the main clause, the comma tends to separate the clauses naturally, as also occurs in well-marked uses of Explanatory Conjunctions.

IdeiaIdea	ExemploExample
Pois justifica a ideia anterior.Pois justifies the preceding idea.	Não veio, pois estava doente.He didn't come, because he was sick.
Isto é esclarece ou reformula o que foi dito.This clarifies or rephrases what was said.	Gosta de leitura, isto é, passa horas com livros.He likes reading; that is, he spends hours with books.
A explicação vem depois da informação principal.The explanation comes after the main information.	Fechou a janela, pois havia vento.He closed the window, for there was wind.

Coordinating conjunctions normally appear between clauses or coordinated terms, organizing the relationship without changing the form of the linked words. In colloquial language, some can start a sentence, especially but, however and and, though this depends on tone and style. The comma is common before adversatives and explicatives, while and generally links the segments without a comma when merely adding information.

IdeiaIdea	ExemploExample
A conjunção costuma ficar entre os elementos ligados.The conjunction tends to sit between the linked elements.	Leu e escreveu.Read and write.
Em uso coloquial, a conjunção pode iniciar a frase.In colloquial use, the conjunction can start the sentence.	Mas ele não concordou.But he did not agree.
A vírgula é comum antes de adversativas e explicativas.The comma is common before adversatives and explicatives.	Estava pronto, mas desistiu.He was ready, but he gave up.

Conjunctions do not vary in gender or number, because they function as connectors and not as agreeing words. The effect is structural and semantic, not inflectional, and therefore the form of the conjunction remains stable. In choices of register, nonetheless and nevertheless tend to sound more formal, while 'e', 'mas' and 'ou' are neutral and very frequent in everyday use.

IdeiaIdea	ExemploExample
A conjunção não flexiona em gênero ou número.The conjunction does not inflect for gender or number.	E ligou as ideias com a mesma forma.And linked the ideas with the same form.
Contudo e todavia favorecem registro formal.Contudo and nonetheless favor a formal register.	Desejava sair, contudo permaneceu.They wished to leave, however they stayed.
E, mas e ou são formas de uso muito comum.And, but and or are very common forms.	Estudou e descansou.Studied and rested.

Coordinating conjunctions link equivalent units and move the sense forward by addition, contrast, alternative, conclusion or explanation. The correct interpretation depends on both the word chosen and its position in the sentence and the punctuation associated with it. In real texts, the value of the conjunction and the choice of register go hand in hand, just as happens in other groups of linkage seen in [Adversative Conjunctions] and [Subordinating Conjunctions].