Capitalization
Capitalization in Spanish is sparse compared to English. In general, only personal and place names, some abbreviations (e.g. Sr. López, but señor López), the first word (only) in the title of a book, movie, song, etc., and the first word in a sentence are capitalized, as are names of companies, government bodies, etc. Names of nationalities or languages are not capitalized, nor (in standard style) are days of the week and months of the year.
Read more about this topic: Spanish Orthography, Orthography