Tapas are a way of life
In many cities, you get a free tapa with every drink. Granada is famous for this. Hop between bars, order a caña (small beer), and eat whatever arrives. In other cities, you order tapas à la carte.
Tip: In San Sebastián, they're called pintxos and are lined up on the bar. Point at what you want. The toothpicks are counted for your bill.