Vowels are sounds made when air flows freely through the vocal tract. In English, the letters a, e, i, o, and u are considered vowels, as well as sometimes y. The sound a vowel makes depends on the shape and position of the tongue and lips.

• Examples:
• The word "apple" has the vowel sound /æ/.
• The word "egg" has the vowel sound /ɛ/.
• The word "ink" has the vowel sound /ɪ/.
• The word "on" has the vowel sound /ɑ/.
• The word "up" has the vowel sound /ʌ/.

Vowels are different from consonants, which are sounds made when airflow is partially or completely blocked.

For more in-depth information, you may refer to these resources:

• EnglishClub - Vowels
• EF Education First - Vowels