What it is: In a sentence, important words are stressed; others are reduced. What it’s for: Better listening and more natural speaking rhythm. Example: “I WANT to BUY a NEW phone.” (main meaning words)

• Content words (stressed): nouns, main verbs, adjectives, adverbs
• Function words (reduced): a/the, prepositions, auxiliary verbs (do/are/have)

• Say it twice:
  1. Slow, clear: “I want to buy a new phone.”
  2. Natural: stress WANT/BUY/NEW/PHONE; reduce “to/a”.

• *reduce* /rɪˈdjuːs/: nói nhẹ/giảm âm
• *auxiliary* /ɔːɡˈzɪliəri/: trợ động từ
• *function word* /ˈfʌŋkʃən wɜːd/: từ chức năng (a, the, to…)