Oregano is a plant that is a species of Origanum, which is native to Europe, the Mediterranean and south Asia. It is a type of perennial herb that grows quite long and has purple petals. It is primarily used for cooking due to its pungent odor. It only needs to be sprinkled on or used sparingly as it can have a strong taste. Widely used in Greek and Italian dishes, it is the leaves that are used and can be cooked fresh or dried.

They are flavorful dried leaves and flowering tops of any of various perennial herbs of the mint family widely used to season many foods. The name is derived from the Greek oros, mountain, and ganos, "joy". Oregano has long been an essential ingredient of Mediterranean cooking. Pliny the Elder thought it a remedy for bad digestion. The aromas, strong and aromatic, and the taste, warm, pungent, and bitter, are prominent in Italian cooking and in robust dishes of certain other cuisines, such as the Mexican chili con carne. In the United States the use of oregano rose sharply in the late 20th century, owing largely to the popularity of pizza. Italians call it the mushroom herb but use it with many other foods as well. The Spanish word oregano means marjoram, and the herbs are sometimes used interchangeably.

Native to the hills of the Mediterranean countries and western Asia, the herbs were brought to the Western Hemisphere in early times and are naturalized in parts of Mexico and the United States. All varieties contain essential oil. In some, the principal component of the oil is thymol, in others carvacrol.

Oregano is used in many tomato sauces, fried vegetables and many types of grilled meat for seasoning used in many Italian dishes along with basil. It can also be combined with spicy food which is unlike many other herbs and spices. In Greek food, oregano is used in the famous Greek salad and is added to the dish after it has been made.

The taste of oregano varies somewhat dependant on where it grows. Generally it has a warm and bitter taste with different intensities. The strongest intensities are the good ones, which almost numb the tongue. In colder weathers, where oregano grows, it is not so strong and the flavor is somewhat an acquired taste. The climate, season, soil, and amount of essential oil in the herb all create different flavors of oregano making it a very diverse herb.

It Italy, apart from being used in regular tomato dishes, it is also a favorite ingredient on pizzas. The fact that in history, the pizza margherita reflected the colors of the Italian flag, green being represented by basil at the time shows the popularity of the dish. Nowadays, oregano is used as a replacement to basil especially on pizzas and is used to accompany toppings such as ham, sausage, anchovies, capers, olives, garlic, onion, mushrooms and shellfish.

The Mexican oregano is very similar to the Italian and Asian oregano that is grown. It has a stronger flavor and is used in dishes such as chili con carne and pozole, which has quite a spicy taste. In health terms, oregano has been proven to be a good antioxidant due to its high quantity of phenol acids. Oregano in some countries is also used as a medicinal plant using the essential oils for health benefits. For example, in the Philippines, the herb is used for relief to children's coughs. The essential oils are also sometimes used in aromatherapy and other therapeutic types of treatment available around the world.