Assonance is a resemblance in the sounds of words or syllables either between their vowels (e.g., meat, bean) or between their consonants (e.g., keep, cape). However, assonance between consonants is generally called consonance in American usage. The two types are often combined, as between the words six and switch, in which the vowels are identical, and the consonants are similar but not completely identical.
A special case of assonance is rhyme, in which the endings of words (generally beginning with the last stressed syllable) differ in their initial consonant, while the rest of the word is identical--as in six and mix or history and mystery. Vocalic assonance is an important element in verse. Assonance occurs more often in verse than in prose; it is used in English-language poetry and is particularly important in Old French, Spanish, and the Celtic languages.
English poetry is rich with examples of assonance:
That solitude which suits abstruser musings
on a proud round cloud in white high night-- E. E. Cummings, if a cheerfulest Elephantangelchild should sit
It also occurs in prose:
Soft language issued from their spitless lips as they swished in low circles round and round the field, winding hither and thither through the weeds.
Hip hop relies on assonance:
Some vodka that'll jumpstart my heart quicker than a shock when I get shocked at the hospital by the doctor when I'm not cooperating when I'm rocking the table when he's operating...
Dead in the middle of little Italy little did we know that we riddled some middleman who didn't do diddly.-- Big Pun, Twinz
Can't tell me shit about the tricks of this trade
Switchblade, with a little switch to switch blades
And switch from a six to a sixteen-inch blade-- Eminem, "Rap Game"
It is also heard in other forms of popular music:
I must confess that in my quest I felt depressed and restless-- Thin Lizzy, "With Love"
Dot my I's with eyebrow pencils, close my eyelids, hide my eyes. I'll be idle in my ideals. Think of nothing else but I-- Keaton Henson, "Small Hands"
Assonance is common in proverbs:
The squeaky wheel gets the grease.
The early bird catches the worm.