For those who have watched me post about this week's ConAgra Catalina deal at Jewel-Osco and been confused, help is here! Here is a full explainer on what Catalina deals are, how to use them to save lots of money on groceries, and some answers to the most common questions. If you have your own Catalina question, add it to the comments and I'll address it. 

Just say "Catalina deal" and experienced bargain grocery shoppers start salivating, while the casual shopper starts wondering what in the heck you are talking about.

Catalinas are a special kind of grocery deal, popularized in the past several years, where shoppers can earn a coupon for money off their next shopping trip by buying certain items today. They get their name from Catalina Marketing, a company that creates a Catalina deal by connecting the manufacturers (who foot the bill for the promotions) with the grocery stores where the stuff is purchased and coupons issued. You see Catalina coupons -- or just "Catalinas" or "Cats," in shopper blog and message board lingo -- print out at special little printers next to the register at the grocery store, and if you look closely, you'll see the name Catalina on the printer.

That printer spits out some ordinary coupons, like for $1 off toothpaste. But if you buy the items that trigger a money-back Catalina deal, you'll get a coupon that you can spend (almost) like cash, for $1 or $5 or even $15 off your next grocery transaction. Hardcore couponers -- like you, if you've been reading Frugalista long enough -- work the Catalina deals so well that they sometimes pay less than $10 to earn a $10 Cat. Then, they turn around and use that $10 Cat to buy more stuff that will trigger yet another $10 coupon, rolling it over and over until the transaction ends and they have a huge pile of groceries for which they paid hardly anything.

Seriously. Here are some of my Catalina hauls. This is a major strategy that I use for keeping my pantry stocked, and it's why you rarely see breakfast cereal, cooking oil or ketchup in one of my ordinary weekly shopping trips.

There are two main kinds of Catalina offers. One is the small Catalina, like, "buy four boxes of granola bars, get a $2.50 coupon, buy five boxes, get a $3 coupon, or buy six boxes and get a $4 coupon." These little Catalinas are sometimes "national deals," meaning that they are offered at lots of stores at the same time. They're nice.

But what bargain shoppers really wait for is the "big Catalina." These are the deals that say, "spend $25, get a $10 coupon" for your next shopping trip. On both the big and little deals, you can use manufacturer's coupons and store coupons to bring the price you pay down, sometimes down below what you get back. There's also another trick for reducing your out-of-pocket expense significantly, which I'll discuss below in the Q&A section.

Before we get to Q&A, here's a dirty little secret of "show bargain shopping" like you see on Extreme Couponing: When shoppers say they saved 99 percent on a grocery trip, they may have used a few or a dozen Catalina coupons worth $5 or $10 each to bring their total down. Say I rang up $100 worth of groceries, and I use a store coupon for $10 off a $100 purchase, plus $39 worth of manufacturer's coupons that I clipped from the newspaper or printed online. That brought my total for $100 worth of groceries down to $51, which is nice, but it won't cut the mustard for showing off on a big TV show. So out of my coupon file I pull four coupons that I earned last week, each one for $10 off any groceries. Now, I'm paying $9 for $100 worth of groceries, and everyone is really impressed, even though you don't see the money I had to spend to earn that last $40 in coupons. I'm not necessarily condemning this practice -- after all I spend Catalina coupons myself on my shopping trips that I share here on Frugalista -- I just want you to keep in mind that it is done.

Now, here are the answers to the most common questions about Catalina deals:

Q: You said I can spend a Catalina coupon "almost" like cash. Why almost?

A: The coupons are usually printed with some restrictions, like that you can't use it on postage stamps, cigarettes or alcohol. Personally, I have never had a problem using them in a transaction that includes alcohol but that's what they usually say. They are also unlike cash in that you will not get change back for a Catalina coupon. So if you have a $10 Cat but you're only buying $8.50 worth of stuff, you'll want to find a "filler" product that costs $1.50 or more or the register will calculate that the store owes you money, and the store don't roll that way. Finally, Cats usually have expiration dates; cash doesn't expire.

Q: How do you find out about Catalina deals?

A: Sometimes they're advertised in the store's weekly ads. Sometimes little coupon-sized alerts print out from the Catalina printer in the store telling you about an upcoming offer. But sometimes Catalinas are active that have not been advertised at all, and you learn about it from blogs like Frugalista.

Q: Is the minimum purchase calculated using the sale price, the card price or the regular price?

UPDATE: As of the end of April 2011, it looks like Jewel has changd the system so that you have to spend the minimum for the deal in the Preferred Card prices. So if the deal says "spend $20," your total of included items really needs to be $20, after you scan your card, before you use your manufacturer's coupons. Here is Jill Cataldo's post about the news.

A: Aha! This question is at the heart of the "secret" way to spend less on Catalina deals at Jewel-Osco and other Supervalu stores.

At most stores, a Catalina deal is calculated based on the sale price you pay with your store card. But at Jewel-Osco, on Jewel grocery products, the minimum purchase is calculated based on the price it rings up at before you scan your Preferred card. This is a very big deal.

Q: Why is Jewel's way of calculating Catalina purchases a very a big deal?

A: Because the price of products at Jewel before you scan your card tends to be crazy high. You can add up the cost of products without the card discount, and when you get to $25, you have enough stuff to trigger the coupon. Then scan your card -- the price you will pay is of course the discounted card price. Taking advantage of the difference between the pre-card price and the card price at Jewel-Osco is known among the devout as "playing the spread," and it sometimes leads to free or even moneymaking groceries.