According to The Joy of Cooking, the original tapas were the slices of bread that sherry drinkers in Andalusian taverns used to cover their glasses between sips. This was a practical measure meant to prevent fruit flies from hovering over the sweet sherry. But soon, enterprising bartenders were putting small snacks on the bread, and the lowly tapa (derived from the word tapar, "to cover") became as important as the sherry.

Tapas evolved over Spain's history through the incorporation of ingredients and influences from many different cultures and countries. The east coast was invaded by the Romans, who introduced the olive and irrigation methods. The invasion of the North African Moors in the 8th century also brought olives to the south, as well as almonds, citrus fruits and fragrant spices. The influence of their 700-year presence remains today, especially in Andalusia. The discovery of the New World brought the introduction of tomatoes, sweet and chili peppers (capsicums), corn, beans and potatoes. These were readily accepted and easily grown in Spain's micro-climates.

In Spain, dinner is usually served between 9 p.m. and 11 p.m. (sometimes as late at 12 Midnight), leaving significant time between work and dinner. Therefore, Spaniards often go "bar hopping" (Spanish: Ir de tapas) and eat tapas in the time between finishing work and having dinner. Since lunch is usually served between 2 and 4 p.m., another common time for tapas is weekend days around noon as a means of socializing before lunch proper at home.

It is very common for a bar or a small local restaurant to have 8 to 12 different kinds of tapas in warming trays with glass partitions covering the food. They are often very strongly flavored with garlic, chilies or paprika, cumin, salt, pepper, saffron and sometimes in plentiful amounts of olive oil. Often one or more of the choices is seafood (mariscos), often including anchovies, sardines or mackerel in olive oil, squid or others in a tomato based sauce, sometimes with the addition of red or green peppers or other seasoning. It is rare to see a tapas selection not include one or more types of olives, such as manzanilla or arbequina olives. One or more types of bread are usually available to eat with any of the sauce-based tapas.

In the northern Spanish city of León, in Asturias, in Extremadura, and in parts of Andalusia, when you go to a bar and order a drink, you get a tapa for free. This happens mostly in the province of Jaén, Granada, Almería and Córdoba but it is not very common in the rest of Andalusia, where you generally have to pay for both the drink and the tapa. Sometimes, especially in Northern Spain, they're also called pinchos (spelled pintxos in Basque) in the Basque Country and in some provinces like Salamanca and Granada. They're called that because many of them have a pincho, or toothpick, through them. The toothpick is used to keep whatever the snack is made of from falling off the bread it has been attached to and to keep track of the number of tapas the customer has eaten. Differently priced tapas have different shape or size toothpicks. Tapa price ranges from 1.00 to 1.50 euros. Another name for them is banderillas (diminutive of bandera "flag"), in part because some of them resemble the colorful skewers used in bullfighting.

In Andalusia, tapas can be "upgraded" to bigger portions, equivalent to half a dish (media ración) or a whole one (ración). This is generally more economical when a tapa is being ordered by more than one person. The portions are usually shared by diners, and a meal made up of raciones resembles a Middle Eastern mezze or Chinese dim sum.