Spanish is synonym of castellano
Initially, the Castilian language was one of several languages spoken
in Spain in the 15th century; at that time Ferdinand of Aragon and Isabella
of Castile reigned in their respective kingdoms, and each spoke their own
language, thus, Castilian was spoken in Castile. When Ferdinand and Isabella
married, their kingdoms were united, Isabella promoted the reconquest of
Spain from Muslim rule and supported maritime exploration which led to the
expulsion of the Muslims and the discovery of America; with these achievements
the Castilian language gained importance and spread both in Spain and in the
American colonies.
Today, the Castilian language is known as Spanish outside of Spain, and is
now considered synonymous. Spanish or Castilian is an elegant and phonetically
beautiful language, and is spoken in 21 countries (see map).Despite the widespread
use of Spanish, there are 6 official languages in Spain: Castilian, Catalan,
Valencian, Galician, Basque and Aranese; but 98.9% speak it as a first or
second language. Globally, 7.1% of the world's population speaks Spanish
(ref. Wikipedia).