There are so many different types, triggered by stress, high blood pressure, vascular defects, muscle spasm and tension, eye strain, and other causes, it would be best to ask a neurologist for the exact cause in your particular case. And if it's about migraine, that's another question all together.
There are several types of headaches and even more cures. The most common type is called a tension headache. You could try an over-the-counter treatment like Tylenol. Make sure you don't exceed the recommended dose, as (depending on which medicine you use) you may damage your liver or kidneys. If the headaches are NOT few and far between, I'd see a dr to find out more about what you can do.