While "merci" is the famous French word for "thank you," its common usage in Catalonia (particularly in and around Barcelona) is actually a linguistic evolution of the native Catalan word "mercès." Over time, "mercès" was shortened and phonetically smoothed out into "merci" due to its phonetic beauty and ease of use. While many outsiders assume it is a direct loanword from French—given Catalonia's proximity to the French border and its historical ties to the Occitan language—linguists categorize it as an internal evolution of Catalan. It is a more casual, colloquial way of saying thanks compared to the more formal "gràcies." In 2026, you will hear "merci" used frequently in shops, cafes, and daily interactions, serving as a unique cultural marker that distinguishes the Catalan language from the Castilian Spanish "gracias."