Over-the-counter (OTC) drugs are medicines that may be sold without a prescription, in contrast to prescription drugs. The name "over-the-counter" is somewhat confusing to some, since these items can be found on the shelves of stores and bought like any other packaged product in some countries or in others may be bought "over the counter" from the pharmacy, while prescription drugs are sold at a pharmacy counter. The term likely dates back to before self service shopping became common, when most goods were obtained by requesting them from a clerk at a sales counter; while prescription drugs required a visit to the doctor first, these drugs could be purchased "over the (sales) counter" just like other goods. Some medicines considered safe in general terms may be available in general stores, supermarkets, gas stations etc. The rules vary considerably from country to country.