High frequency words are words that appear a lot (with frequency) in the texts that students read. They may have irregular spellings (different from what we’d expect)— like of or the— or they may have regular phonic relationships— like can or at. These are compiled into lists like the Fry list or Dolch list. (Click here to learn more about these lists.)
Sight words refers to any word that is recognized automatically. For adult readers like us, almost all words are sight words because we can read them with automaticity.
Snap words are one curriculum’s (Units of Study) umbrella term for both sight words and high frequency words. This term is drawn from the phrase, “In a snap!”