The English alphabet has 26 letters traditionally ordered: a b c d e f g h i j k l m n o p q r s t u v w x y z, a set of visual marks or symbols that represent oral sounds. Letters when combined can form words with meanings. Words can be ordered to form sentences.
This modest set of marks and sounds has been sufficient to write every book, drama, journal, script, manual, correspondence, text that has ever been written and every word ever spoken in the English language. (Similarly with other languages.)