The population of Spain doubled during the twentieth century, but the pattern of growth was extremely uneven due to large-scale internal migration from the rural interior to the industrial cities.

In 2022, the average total fertility rate (TFR) across Spain was 1.16 children born per woman.

[6] The data shows that more women than men chose to move to Spain during 2022, this is due to higher rates of emigration from Latin America.

[6] Notable events in modern Spanish demography: The population of Spain doubled during the twentieth century as a result of the demographic boom in the 1960s and early 1970s.

Many demographers have linked Spain's very low fertility rate to the country's lack of a family support policy.

[12] The arrival of migrating young adults was the main reason for the slight increase in Spain's fertility rate.

The term "Spanish people" (pueblo español) is defined in the 1978 constitution as the political sovereign, i.e. the citizens of the Kingdom of Spain.

The same constitution in its preamble speaks of "peoples and nationalities of Spain" (pueblos y nacionalidades de España) and their respective cultures, traditions, languages and institutions.

[citation needed] The native Canarians are partly the descendants of the North African population of the Canary Islands prior to Spanish colonization in the 15th century although many Spaniards have varying levels of North African admixture as a result of the Islamic period.

Also included are many Spanish citizens who are descendants of people from Spain's former colonies, mostly from Venezuela, Argentina, Dominican Republic, Ecuador, Peru, Colombia, Morocco and Cuba.

Historically, Sephardic Jews and Moriscos are the main minority groups originating in Spain and with a contribution to Spanish culture.

[53][54] Spanish missionaries carried Catholicism to the Americas and the Philippines, establishing various missions in the newly colonized lands.

[59] As of 2018[update], 68.5% of the population define themselves as Catholic, 26.4% as non-believers or atheists, and 2.6% other religions according to the official Spanish Center for Sociological Research.

[62][63] There have been three Popes from what is now Spain, all of them from the Crown of Aragon: Calixtus III, Alexander VI and Benedict XIII.

Spanish mysticism provided an important intellectual resource against Protestantism with Carmelites like Teresa of Ávila, a reformist nun and John of the Cross, a priest, taking the lead in their reform movement.

The Society of Jesus was co-founded by Ignatius of Loyola, whose Spiritual Exercises and movement led to the establishment of hundreds of colleges and universities in the world, including 28 in the United States alone.

[64] The recent waves of immigration have also led to an increasing number of Muslims, Buddhists, Sikhs and Hindus.

[citation needed] Judaism was practically non-existent in Spain from the 1492 expulsion until the 19th century, when Jews were again permitted to enter the country.