Definite articles and preposition contractions
Every Portuguese noun is masculine or feminine, and the article has to match: o for masculine, a for feminine, plus an -s for the plurals os and as. Then comes the part that makes a page of Portuguese look unlike Spanish: prepositions fuse with the article. de + o is not 'de o', it's do. You can't route around these contractions — they're how Brazilians actually speak and write.
The four definite articles
o = the, masculine singular: o gato, o pão, o café. a = the, feminine singular: a casa, a água, a cidade. os = the, masculine or mixed plural: os amigos. as = the, feminine plural: as casas. Use them wherever English uses 'the' — plus a few places English doesn't, which we'll meet as they come. The sounds are tiny: o is 'oo', a is 'ah', and in Brazil both of them stay clear instead of fading away.
Articles before names — a regional habit
Brazilians often put an article in front of a first name: a Ana está aqui, o Pedro é meu amigo. It's warm and completely normal in São Paulo, Minas, Rio and the South. Much of the Northeast leaves it out, and formal writing drops it everywhere — Ana está aqui. Neither version is a mistake, so pick one and stop worrying. (Portugal, for what it's worth, uses the article almost always.)
de + article → do, da, dos, das
The preposition de ('of' / 'from') always fuses with a following article. de + o = do; de + a = da; de + os = dos; de + as = das. a casa do Pedro = Pedro's house. a mãe da Ana = Ana's mother. o gato dos amigos = the friends' cat. Portuguese has no apostrophe-s, so this is how you show possession — the owner goes second. You'll never write 'de o': it's always one word. And hear the Brazilian de: 'jee'.
em + article → no, na, nos, nas
Same fusion with em ('in' / 'at' / 'on'). em + o = no; em + a = na; em + os = nos; em + as = nas. Estou no café. = I'm at the café. Estou no ônibus. = I'm on the bus. A água está na geladeira. = The water is in the fridge. One idiom breaks the pattern: 'at home' is em casa, with no article at all — just like English drops 'the'. Note also that where Portugal says 'em casa da Ana', Brazil says na casa da Ana.
a + article → ao, à, aos, às
The preposition a ('to', for direction) fuses too. a + o = ao; a + a = à, written with a grave accent so you can tell it apart from the plain article; a + os = aos; a + as = às. Vou ao café. = I'm going to the café. Vou à cidade. = I'm going to the city. That accent is called the crase, and in writing it isn't optional — though a and à sound identical, so nobody can hear you get it wrong. Fair warning: in casual Brazilian speech people constantly say vou no café instead of vou ao café. Everyone does it; every teacher corrects it. Write ao and à.
