English phonology refers to the study of English phonology (that is, phonetic system). Just like all languages, regardless of history, the pronunciation of spoken English varies from dialect to dialect.

English is famous for its huge vocabulary, and it is easy to introduce technical terms and enter new words in daily use. In addition, slang gives new meanings to old words.

This flexibility is very obvious, and it is usually necessary to correctly distinguish between formal usage and daily general usage; Primary education teachers in Britain and the United States generally remind students of words that are widely used in daily life but are not correct in formal occasions.

English is written in Latin alphabet, also known as "Roman alphabet". The spelling system or correct spelling of words is inherited according to historical traditions, not strictly according to pronunciation rules.

Therefore, the pronunciation and spelling of English words are often very different, and word spelling is one of the most difficult words in all alphabet languages. Latin alphabet, Slavic alphabet and Arabic alphabet are called the three major alphabet systems in the world.