What exactly is utilitarianism, I thought the aim of all philosophy was to make us happy?

Utilitarianism is different from other moral theories because it sees happiness alone as the sole aim. Many other theories see duties as overriding happiness, and perhaps elevate virtue, honour or religious dedication above happiness. Utilitarianism on the other hand attempts to suggest these things are only instrumentally useful in the fact that they bring us happiness, and alone as of no use.