The little portions of food served to accompany a drink in bars in Spain are popularly known as tapas. The use of this term as a synonymous of aperitive has an uncertain source:

• There are sources that locate its origin in the Andalusian ventas (roadside inns), and it is told that, in order to accompany sherry and aromatic wines, thin slices of chacina (cured meat) began to be used to avoid evatoration of the wine´s aroma (due to this region's temperatures) by placing them on the cups.

• Other people think that this practice would come from protecting the wine from insects to fall inside it.
  

• And there are people who argue that it comes from an anecdote played by the king Alfonso XIII when visiting Cádiz.

Before he returned to his castle, the king stopped at the Ventorrillo del Chato, venta that still exists today at the beach named that way, between Cádiz and San Fernando.

Alfonso XIII ordered a cup of Jerez wine (sherry), but he was not aware of a whirlwind slipping into the site and menacing to pollute his wine with beach sand.Trying to prevent this, a diligent waiter rushed to cover (in Spanish: tapar) the cup using a cured ham slice.

When the king got ready to taste his wine, he asked surprised: What is this? The waiter answered: "Please excuse my boldness your majesty, I have placed a cover (tapa) there to protect it from the sand".

King Alfonso XIII ate the cured ham slice and ordered another wine, but "with the same cover".

Everyone there laughed with the king´s inventive and emulated him ordering the same.

Bibliography: Extra "El libro de los orígenes", magazine "Muy Interesante" , nº226

"Tapas de la cocina española" , Itos Vázquez , Editorial EVEREST