Subordinating Conjunctions

que that
mientras as, while
cuando when
donde where
desde que since (indicating time)
mientras que while, whereas
como since
porque because
apenas as soon as

Subordinating conjunctions introduce subordinate, or dependent clauses; these are clauses that cannot stand alone because their meaning depends on the main clause. For example, in the sentence below, the main clause ellos ya saben casi todo is a complete idea that can stand alone, while the two subordinate clauses porque aprendieron cuando eran niños and cuando eran niños need the main clause for context.

Ellos ya saben casi todo porque aprendieron cuando eran niños.
They know almost everything because they learned when they were kids.

These conjunctions may occur with other tenses besides the present, including the futureconditional, and imperfect. There are other conjunctions which require the subjunctive: para que, sin que, antes de que, a menos que, con tal de que, en caso de que.

A menos que a usted le guste pizza de papel o de cartón, no lo recomiendo.
Unless you like pizza made from paper or cardboard, I do not recommend it.