Spanish Subjunctive

In modern English the subjunctive is barely used. It's only used to express a hypothesis already consider impossible (If I were you) or a wish (God save the Queen!), and in some expressions such as "Be that as it may", "Come what may", etc.

On the other hand, I think the Spanish subjunctive is used a lot in everyday speech, not only in poetry (as some people believe). Let me explain a little bit about it.

This mood is used to present things as possible or doubtful in subordinate and independent clauses. The subject of the subordinate clause must be someone or something else, different than the subject of the main clause.

It's required in subordinate clauses dependent on

1. Verbs or other words expressing:
   
   
   • desire (Quiero que lo hagas / I want you to do it),
     
   • request (Me pidió que lo hiciera / He asked me to do it),
     
   • command (Me ha ordenado que lo haga / He has ordered me to do it)
     
   • permission (No permitieron que lo hiciera / They didn't allow him to do it)
     
   • prohibition (Nos prohibieron que lo hiciéramos / We were forbidden to do it)
     
   • advice (Te aconsejo que lo hagas / I advice you to do it)
     
   • causation (Esto hizo que me perdiera / This made me lose my way)
     
   • emotions, such as regret, fear or surprise (Sinte que no lo hayamos podido hacer / I'm sorry we were unable to do it; Es extraño que no haya llamado / It's strange that he hasn't called)
     
   • uncertainty or negation (Quizá no lo venga / He might not come)
     
   • preference (Prefiero que lo hagas ahora / I would rather that you do it now)
     
   • necessity or obligation (Es necesario que todos cooperemos / We must all cooperate)
   
   
2. Impersonal expressiones of probability (Puede ser que lo consigas / You might succeed)
   
   
3. Conjunctions wich introduce future or hypothetical action (Cuando termines llámame / Call me when you finish), including antes (de) que (before), para que (in order that), con tal que (provided that), A no ser que (unless), no porque (not because), como si (as if), etc.
   
   
4. A relative pronoun with a negative or inefinte antecedent (No hay excusa que valga / No excuses; Haré lo que pueda / I shall do my best)
   
   
5. Conditional clasues (¿En dónde estaría ahora si no te hubiera conocido? / Where should I be now had I never met you?)

In addition, the present subjunctive is used for the imperative -except for the second person- (Cantemos / Let's sing), as well as for all persons in the negative (No cantes / Don't sing).