Here's a breakdown:
* Syllable: A unit of pronunciation that consists of a single vowel sound, with or without surrounding consonants.
* Onset: The part of a syllable that comes *before* the vowel. It's the initial consonant(s) in the syllable.
Examples:
* "cat" has an onset of "c" and a vowel of "a".
* "straw" has an onset of "str" and a vowel of "a".
* "eat" has an onset of "e" and a vowel of "ea". (Remember, "ea" acts as a single vowel sound in this case).
The onset is important in phonology (the study of sounds in language) because it can influence the pronunciation of the vowel that follows. For example, the vowel sound in "cat" is different from the vowel sound in "cot" due to the difference in the onset.