Do you have to pay to be on podcasts?

Are there any fees associated with being a guest on podcasts? Is there a standard cost for appearing on these platforms, or does it vary depending on the podcast and its audience? As someone interested in expanding my reach through podcast appearances, I'm curious about the financial aspect of this opportunity. Is it a common practice for podcast hosts to pay their guests, or is it more of a mutually beneficial exchange where both parties benefit from the exposure?