Why do poets use syllables?

Answer 1

Poets use syllables in different ways. But syllables are normally used to keep the poem in the rhythm.

An example would be:

There once was a cat

With a purple hat.

The lines rhyme and each have five syllables.

There was a cat

With a big, sparkly, beautiful, dazzling, purple hat.

The lines rhyme, but since one line has four syllables and the other has 13 syllables, the poem doesn't sound as good.