Consider the comma, most used of all marks.
In back of a word,
You will notice,
It parks
And waits for the reader and tells him or her to pause
Before, let us say,
He or she begins a new clause.

Its head on the line and its tail hanging down,
It looks like a polliwog trailing a noun,
And, having no arms,
There it clings by its chin,
Amidst the fat words looking tiny and thin.

Yet small though it is,
It shows lion-like heart
In keeping two parts of a sentence apart
And helping the reader, down wordways careening,
Get just the right emphasis,
Just the right meaning.

It doesn’t say, "Stop!"
It says, "Caution" or "Slow,"
And this can be very important, you know.