A Limerick typically has 5 lines
The 1st, 2nd and 5th line rhyme (and have 8/10 syllables)
The 3rd and 4th line rhyme (and have 5/6 syllables)
Another example:
'When the wind in the trees starts to blow
And you hear the leaves rustling below,
Then a chill in the air
Says it’s time to declare
Let it snow, let it snow, let it snow.'