Do employment agencies charge a fee to the people they are employing? -

Specifically Kelly Services Inc, although im sure they all work the same way. Do they take a portion of your paycheck or is it just the company that has to pay them?

They sell your services to a company for say $30 per hour. In turn, the agency will pay you $20 per hour and keep $10 per hour for themselves. That is how they earn their money.