Hi Rocío, "Trust someone/something" = be able to rely on someone. E.g. "Don't let me down. I trust you." "I wouldn't trust anything he says; he's a liar." "You can't always trust Wikipedia." "Trust in" has a similar meaning (to depend on, to rely on), but is only ever used in very formal contexts, and followed by god or some idea/concept. E.g. "She trusted in the powers of justice." or "In God we trust" It's a bit like "believe" and "believe in". The first one is commonly used; the other one again refers to one's faith or strong convictions. ("I don't believe you" / "I don't believe it" vs. "I believe in God." / "I don't believe in capital punishment.")