two adjacent vowel sounds can be blended together into a single syllable called a diphthong

the letter "W" by itself is not usually a vowel, but can form a diphthong with the vowels "A", "E", or "O"

the five primary vowel letters can represent both "long" and "short" vowel sounds (some of the long vowel sounds in English are actually diphthongs)

some vowel sounds are represented by combinations of vowel letters, such as "ou" in words like "through" or "thought"

English, makes extensive use of combinations of vowel letters to represent various sounds

vowels support the neighboring consonants, but often bear little information themselves (cn y rd ths?)