Spanish si clauses, also known as conditionals or conditional sentences, are used to express what could happen if some condition is met. There are three different kinds of si clauses. But they can just be summarized as if-then clauses.
Si clauses indicate possibilities, which may or may not become reality. They refer to the present, past, and future. These conditional sentences have two parts: the condition, or Si clause, and the main or result clause which indicates what will happen if the condition of the Si clause is met.
The tense of the result clause depends on the tense of the Si clause. In other words, the tense of the two clauses follow a prescribed sequence.
