There are several studies that show that having a coupon field in your checkout process can actually lower conversion rates. When people see a coupon field, they assume they can find a coupon somewhere online and they'll leave your site looking for a coupon. It's better to hide the field and give your special customers a discount another way.

Using URL Coupons, we can share special URLs like http://mysite.com/holiday2015 to give people a special discount. These URLs could be shared on your newsletter, via social media, on business cards, or even mentioned on podcasts.