Viagra is one of the most famous and widely used medicines available, and it is basically a drug that is used to treat impotence or erectile dysfunction in men. Viagra increases the flow of blood to certain areas of your body, including the penis, but only if you are sexually aroused. How it does this is a mixture of chemistry and biology, as there is a certain enzyme found only in the penis, and this enzyme hinders the relaxing of arteries in the penis. Viagra temporarily disables this enzyme till it is in your system, and makes it easier to get an erection. You can now buy Viagra online to save yourself the hassle or embarrassment of getting it in person.