The three reasons the Spanish had for colonizing are usually listed as "gold, god, and glory."
"Gold" meant that one of the goals of Spanish colonization was to find gold or to otherwise get economic benefits from the colonies.
"God" meant that one of their goals was to spread Christianity. This was a goal that they emphasized very strongly at least in their rhetoric.
"Glory" meant that both the individual explorers and the country of Spain wanted to gain glory and power. The people wanted to become famous and powerful (along with getting rich). The country of Spain wanted the glory and power than came with having the world's largest empire.
The Spanish had several goals when they established colonies in the Americas. One goal had to deal with economics. The Spanish was hoping to find resources, mainly gold and silver, that would be a boost to their treasury and to their economy. The Spanish did find a lot of gold and silver in the Americas. Establishing colonies would also allow Spain to increase its trade. This would also benefit the Spanish economy.
Another reason for establishing colonies in the Americas was to spread their religion. The Spanish were Catholic and they wanted to do missionary work and spread the Catholic religion. Much of Central and South America today practices the Catholic religion because of the efforts of the Spanish.
Finally, Spain wanted more land to control so they could compete with their rivals. Great Britain and France had established colonies in the Americas, and Spain wanted to do so also. Spain was competing with other European countries for power and control throughout the world. They wanted colonies in the Americas to be on the same level as Great Britain and France, as well as other colonial powers.
Spain had many reasons for establishing colonies in the Americas.
There are three dominant reasons as to why the Spanish colonized the Americas. First and foremost, there was a strong need for the monarchy of Spain to expand its empire because of growing threats from England, France and Russia who were also out to expand their own territories. Secondly, the Spanish colonization of the Americas was motivated by the need to spread of Christianity. Religion was the strongest driver of its colonial activities and has been noted to have surpassed other goals such as the spread of the Spanish language. The colonial territories had established religious structures in the form of churches and missionaries who worked to suppress the existing beliefs of the natives. Thirdly, the Spanish colonized the Americas because they needed to advance their economy. This goal was achieved during their voyages when they struck gold in the Americas.