Assonance is the repetition of vowel sounds within words, usually close to each other.
Here are some examples:
* "The cat sat on the mat" - Repetition of the short "a" sound
* "The rain in Spain falls mainly on the plain" - Repetition of the long "a" sound
* "The old crow flew over the green meadow" - Repetition of the long "o" sound
Assonance is used to create a sense of rhythm, melody, and mood in writing. It can also be used to emphasize certain words or ideas.