If you want to discount an item there are various ways to do this.
You can very simply manually edit the price to a lower value, this is the most basic way to do this.
To make a price reduction stand out, we recommend doing a "sale" which will reduce the price, but also show the original price, crossed-out, alongside the sale price, and add a "sale" mini banner on the main product image. This has the advantage of clearly highlighting what is on sale against an array of products, there is also nothing for the customer to do to take advantage of the offer.
If you are running a sale on a variety of products, we recommend grouping them all in a Tag, and displaying them in a grid on your homepage.
If you have a very large amount of items on sale, the more you enable easy browsing of the products, by grouping them into relevant sections eg "10% off" and "half price", the easier it will be for your customers to make an informed choice about their order.
If you want to limit the price reduction to people who have received marketing creating a voucher allows you to restrict who receives the offer.