The document discusses the irregular pronunciation of the letter combination 'ough' in English. It notes there are 6 variations in American English and 10 in British English. It then provides examples of words containing 'ough' and how they are pronounced, including as /oʊ/ (dough, through), /uː/ (through, throughout), /ɔː/ (bought, thought), /aʊ/ (bough, drought), /ɒf/ (cough, trough), and /ʌf/ (enough, rough). It explains the history behind some of the pronunciation changes and encourages practicing pronouncing the example words to learn the variations of 'ough'.