Making a fancy ad for your product or service on a website is one thing, getting people to actually click on them and buy or sign up is another. Conversion rate represents the percentage of users who visit your page or click on your ad and then take the desired action i.e. sign up to your newsletter or buy your product.
For example…
Take Reading is Cool Bookshop’s ad that promotes their massive sale and offers 25% off any book purchased. If 10,000 people visit by clicking their ad and only 200 end up buying a book and getting the discount, their conversion rate is 2%.