An affiliate program is something you sign up for, post text and images to product links and will make a commission on if someone buys a product or service that you direct them to. Affiliate programs IDs in the links as well as cookies for keeping track of where the traffic came from. The affiliate will give you text and / or images links that you will use to promote their products or services.
Example of an image link:
Example of a text link:
You can choose what you want as the anchor text for your link. This link will point directly to a landing page for the affiliate.
Depending on the terms and conditions of the affiliate, you can use these links on your site or maybe include them in email marketing and social media campaigns.