While many of us use the odd coupon or promo code, some people take it to an extreme, systematically collecting them and deploying them in the most effective way possible.
This can mean using a product money-off coupon, for example, along with a supermarket coupon for free delivery or an extra ten percent off.
On the HotUKDeals website, extreme couponers share their tips - and their successes. "Items in trolley £50.35; delivery price £0.00; voucher savings £-37.72; total price £12.63," boasts one.
Another explains how Sainsbury's customers can add £12 worth of free items to a £28 basket, and pick up cheap delivery at the same time.
Get Sainsbury's vouchers and discounts on AOL Deals
Other examples include using a manufacturer's money-off coupon in combination with a buy one, get one free (BOGOF) offer from a store - netting you both products at the reduced price.
Voucher stacking can't be done everywhere, as some stores specify that only one offer may be used at a time. And some couponers report that store staff don't necessarily know their official policy; it may be worth making sure you do, and even taking along a printed copy.
So where can you find all these coupons and codes? Well, you're already in the right place. Just click on the word 'deals' near the top of this page (or here). Other sources are newspapers and magazines - especially supermarkets' own publications - and product packaging.
Social media can be a good source of discounts: just follow the brands and stores you're interested on Twitter, or 'like' them on Facebook. If you're not too fussed about privacy, you can even choose to share your location with some companies, which will then beam offers to your phone as you're passing their stores.
Read more on AOL Money:
Company's bizarre response to voucher glitch
Save £700 on food without scrimping
Getting a bargain, without having to haggle