Spain has a population of around 48 million, making it the fifth-largest country in the EU by population. It is less homogeneous than many outsiders assume.
Regional identities are strong and politically charged. Catalans, Basques, and Galicians have their own languages, cultural traditions, and, to varying degrees, aspirations for greater autonomy or independence. Castilian Spanish is the national language, but Catalan is spoken by around 10 million people in Catalonia, Valencia, and the Balearics; Basque (Euskara) by around 750,000 in the Basque Country and Navarre; and Galician by around 2.4 million in the northwest. Using a few words in the regional language is appreciated, not mocked.
Religion has historically been Roman Catholic, but Spain is now largely secular in practice. Religious observance has declined sharply since the Franco era, though the Church retains cultural and institutional influence. The festivals of Semana Santa, patron saints' days, and local romerías (pilgrimages) remain important community events regardless of personal belief.
Social life is lived in public. The bar is an extension of the living room — Spaniards meet friends for a coffee or a caña (small beer) standing at the counter, often several times a day. Dinner at 10pm is not unusual; nightclubs don't fill until after midnight. This schedule takes adjustment if you're used to northern European rhythms.
Immigration has transformed Spain since the 1990s. Significant communities from Morocco, Latin America, Romania, China, and sub-Saharan Africa have settled in the major cities and agricultural regions. Spanish cities are noticeably multicultural in ways that were barely visible a generation ago.
Spaniards are generally warm and helpful to visitors, especially if you make any effort with the language. The stereotype of mañana indifference is mostly wrong — Spanish bureaucracy can be slow, but people are not.