Related topics: savings, consumer guide, spending, online shopping, Donna Freedman

Well, the average user at Savings.com spends 60 seconds and saves 30%. Over at Coupon Cabin, shoppers generally spend 80 seconds to save an average of $19. The average RetailMeNot user saves $21 per shopping trip, co-founder Guy King says.

"This is an easy, easy way to save significant money," says Scott Kluth, the founder of Coupon Cabin.

Discount codes from FatWallet, Savings.com, Sunshine Rewards, Rather Be Shopping and RetailMeNot work just like coupons. They can cut the cost of a purchase, add a free item to your cart, provide free or cheap shipping, or offer a break on your next shopping trip.

Anyone who's embarrassed to use coupons will love this part: No one has to know. Then again, you may want to brag about how little you paid.

Code talking

There are five basic types of online discount codes:

• Percent off. This is a straightforward discount. Sometimes there are minimum-purchase requirements or exclusions of specific brands.
• Dollars off. Usually these have minimum-purchase requirements -- for example, $10 off an order of $50 or more
• Free or fixed-price shipping. This is an especially good deal for heavy items. A minimum purchase sometimes applies.
• A gift. An extra item added to a specific purchase, such as a cosmetics bag with the purchase of makeup.
• Good on your next purchase. Deals such as "$10 off your next order with a $50 purchase now" aren't as common as the other four.

In addition to sites such as FatWallet, shopping codes can be found on grocery coupon sites and on freebie and bargain blogs. Online retailers distribute them via e-mail and catalogs, and on social-media pages.

You could also do an Internet search for a phrase such as "coupon code." However, this can lead to a bewildering number of results. I typed "free shipping codes" into Bing and got 138 million possibilities.

It doesn't really matter where you look because the same discounts show up virtually everywhere. Retailers sometimes make exclusive deals with certain sites, but these "vanity codes" are often shared. In fact, some discount-code aggregators encourage users to share all the deals they find.

Readers contribute 95% of the codes on RetailMeNot, according to co-founder King. Users also provide feedback on discounts that have expired or changed.

Although the recent downturn has increased hits, King notes that traffic had already been growing rapidly before the economy went south.

"I think it's just a cultural shift," he says, "where people are more comfortable using coupons than they used to be."

Savvy deal seekers

FatWallet fans frequently post combo deals -- sale price plus discount code plus cash back -- in the site's reader forums. If you see an item you want to buy, be sure to read the entire thread; users sometimes post codes halfway through or let readers know that a posted code has expired.

"The deal hunters in the community are pretty savvy," FatWallet spokesman Brent Shelton says.