It's a term of endearment used to express affection and closeness. It can be used for:
* Romantic partners: "Mi querido" (My beloved)
* Family members: "Querido hijo" (Dear son)
* Friends: "Querido amigo" (Dear friend)
* Pets: "Querido perro" (Dear dog)
It's also used in formal situations, like:
* Letters: "Querido señor" (Dear sir)
* Titles: "Querido lector" (Dear reader)
It's important to remember that the tone of "querido" can change depending on the context and the relationship between the speaker and the recipient.