What Is A Rhyme Scheme?

A rhyme sheme is pretty much a guideline for rhyming poetry, like ABA or AABBAA.  There are many rhyming schemes used in poetry.  The A's and the B's indicate the rhyming, saying that all the lines that are A's will rhyme with all the other lines that are A's.  And all the lines that are B's will rhyme with all the other lines that are B's.  And example might be a simple ABA rhyme scheme:
Up and down,   ---This is line A
Creepy crawlies crawl,  ---This is line B
All the way through town.  ---This is line A

That sounds cheesy, but it's a good example of a rhyme scheme.  You see that "down" and "town" rhyme.
Rhyme schemes can get complicated with A's B's and C's, maybe even D's.  But a line must rhyme with its counterpart.

Rhyme is an important quality while forming verses. One needs to have more than one line of verse to form a rhyme. Rhyming is used both in poetry and prose to create sounds that are pleasing to the ear. A rhyme is used at the end of a line to echo with the end of a previous line. Examples of rhymes are stand-hand, hold –behold, big-fig, run-stun etc. The intrinsic quality of rhymes is the similarity of sounds among words.

Rhyme scheme is a pattern of rhyming lines in a poem or musical piece. It is generally referred to by letters to indicate the lines which rhyme. For instance, 'abab' is a four line stanza in which there is a rhyming between the first and third line. The rhyming scheme 'aa bb cc dd' is used for couplets. Limericks have a rhyming scheme which goes 'aabba.'