In Catalan grammar, the conditionals theory refers to the structures used to express hypothetical or unreal situations. There are three main types of conditionals: the zero conditional, the first conditional, and the second conditional.

The zero conditional is used to talk about general truths or scientific facts. It is formed by using the present tense in both the if-clause and the result clause. For example, “If it rains, the streets get wet” translates to “Si plou, els carrers s’humitegen.”

The first conditional is used to talk about real or possible situations in the future. It is formed by using the present tense in the if-clause and the future tense in the result clause. For example, “If you come to the party, I will be happy” translates to “Si vens a la festa, seré feliç.”

The second conditional is used to talk about unreal or hypothetical situations in the present or future. It is formed by using the imperfect tense in the if-clause and the conditional tense in the result clause. For example, “If I had more money, I would travel the world” translates to “Si tingués més diners, viatjaria pel món.”

Understanding and using these conditionals correctly is essential for expressing different types of situations and ideas in Catalan.