For many shoppers who are serious about spending less on groceries, a trip to discount supermarket Aldi is a weekly ritual. The chain, founded in Germany, credits its rock-bottom prices to low labor and operating costs, a limited selection of mostly inexpensive private brands, and a no-frills store design. Merchandise is often stacked in the aisles and sold straight from the cardboard box it was shipped in. Essentially, it's a grocery store that's the size of a convenience store.

If there isn't an Aldi near you, don't be surprised if one pops up soon. Currently, there are nearly 1,500 stores in 32 states, mostly in the eastern half of the U.S. By 2018, the company plans to expand its store count to close to 2,000 including locations in Southern California.

Never shopped at Aldi before? Here are 10 things you should know before your first trip.

Trader Joe's is part of the family

Trader Joe's and Aldi are owned by sister companies Aldi Nord and Aldi Sud. Aldi Nord owns Trader Joe's, which it acquired in 1979, and operates Aldi stores in Europe. Aldi Sud operates Aldi stores in the U.S. The first one opened in Iowa in 1976.

Aldi was founded in Germany by brothers Albert and Theo Albrecht. The brand name is a combination of the first two letters of their last name and the first two letters of the word discount. The brothers, now deceased, launched their grocery empire right after World War II, but chose to split the business in 1961 reportedly due to a dispute over whether to sell cigarettes.

It's one of the world's biggest retailers

Aldi might not be a household name in the U.S., but it's well known around the globe. In the 2015 Global Powers of Retail Report, which identifies the 250 largest retailers in the world by retail revenue, Aldi ranked eighth globally, finishing ahead of Target and Home Depot. Walmart topped the list; Costco came in a distant second.

In the U.S., Aldi's nearly 1,500 locations outnumber better-known supermarket chains including Whole Foods, Trader Joe's, Publix, Meijer, Food Lion and Giant. Albertsons (thanks to its acquisition of Safeway) and Kroger each operate more locations than Aldi, which plans to open 25 stores in Southern California by July as part of a westward expansion.

You have to bag your own groceries

As part of its low-price business model, Aldi keeps a limited number of staff on the clock at any given time (typically just three to five people). This means that certain conveniences common at larger supermarket chains, such as having groceries bagged for you, is the responsibility of the customer.

You'll want to bring your own reusable shopping bags to pack up everything you've purchased. Otherwise, you'll have to buy shopping bags when you're ready to check out. At Aldi, plastic shopping bags can cost 10 cents each, while paper can run 6 cents per bag.

You need a quarter to use a shopping cart

While shopping carts at most grocers are free for the taking, Aldi requires a 25-cent deposit to use a cart. The cart rental system is simple: To release a cart for your use -- the carts are chained together -- insert a quarter in the coin slot on the cart and the locking mechanism will disengage. When you return the cart and reinsert the chain, the quarter is returned. (Watch this YouTube clip to see Aldi's cart rental system in action.)

Why all the fuss over a quarter? Aldi says it saves money, which it passes along to shoppers in the form of lower prices, because it doesn't have to pay employees to wrangle stray shopping carts from the parking lot. If you want to avoid the 25-cent deposit altogether, it's OK to bring your own collapsible cart.

Nine out of 10 items are store brands

More than 90% of the products found at Aldi stores are private brands, including organic and gluten-free brands. The company gets many of its store-brand products from the same food manufacturers that make name-brand products, says Lauren Greutman, founder of frugal living Web site IAmThatLady.com, meaning quality and taste are often comparable.

Aldi carries far fewer products than a typical supermarket -- 1,300 items versus 30,000 -- so stores are smaller and cheaper to operate, allowing the savings to be passed along to customers. "[Aldi] typically focuses on the most popular product items and package sizes," says Jon Springer, retail editor for Supermarket News magazine.

Shoppers can find a small inventory of name-brand products, too. Name brands stocked by the chain include Coca-Cola, Oscar Mayer, Gatorade and Tide, says Liz Ruggles, the company's director of public relations.

Store brands are cheaper than name brands

Aldi claims shoppers can save up to 50% by switching to its store brands from national brands, based on its own price comparisons. We decided to put Aldi's claim to the test. At a Washington, D.C.-area Aldi, a 13-ounce bag of Clancy's restaurant-style tortilla chips cost 99 cents, while the same size package of Tostitos cost $2.98 at a nearby Walmart. A dozen Goldhen eggs costs 99 cents at Aldi, while a comparable carton of Sunny Meadow eggs totaled $2.48 at Walmart. A 10-ounce container of Little Salad Bar Classic Hummus was $1.99 at Aldi, while Sabra hummus cost $2.98 at Walmart. Bottom line: The three items we priced were 53% cheaper at Aldi than at Walmart.

Everything isn't always cheaper at Aldi, however. Since you can't use coupons at Aldi, Cindy Livesey, founder of Web site LivingRichWithCoupons.com, says you may be able to find better deals on such items as cereal and paper goods at a grocery store that does accept them. This is especially true when you combine manufacturer coupons with supermarket sales.

Not satisfied? Get a replacement and a refund

Aldi's "Double Guarantee" policy is designed to ensure that customers are completely satisfied with their purchases. Say you buy a box of store-brand cereal from the discount grocer and end up hating it compared to your usual name-brand cereal. Simply return the cereal, including original packaging, to the store manager to receive a full refund and a replacement item.

Note that Aldi's guarantee does not apply to certain items including alcohol and national name-brand products.

Multiple bar codes make checkout faster

You'll notice that all of Aldi's store-brand products have multiple barcodes on them. This is intentional, says Ruggles, the Aldi spokeswoman. The design allows for a quicker checkout, because Aldi cashiers don't have to waste time searching for a single barcode to scan on each item in your shopping cart.

That's not the only way Aldi shoppers can save time. Since product selection is limited, stores are smaller than traditional supermarkets, and layouts are consistent from store to store, it can be faster to find everything on your shopping list at Aldi.

Checks and coupons aren't accepted

If you're planning a trip to Aldi, remember to leave your checkbook at home. As part of its effort toward speedier checkout, the grocer only accepts cash, debit cards and (as of March 1, 2016) credit cards for payment. Remember, too, that coupons aren't accepted.

If it's any consolation, these restrictions can get you through the line faster since the person in front of you won't waste time filling out a paper check, fishing for an ID or scanning multiple coupons.

Stores are only open during peak hours

Aldi locations operate during peak shopping hours, which typically means they aren't open as early or late as larger competitors. The company's rationale: "Staying open later would simply add to labor costs -- and raise our prices."

The Washington, D.C.-area Aldi store we visited operates weekdays from 9 a.m. to 9 p.m.; Saturdays from 9 a.m. to 8 p.m.; and Sundays from 9 a.m. to 7 p.m. The nearby Walmart Supercenter is open daily from 6 a.m. to midnight.

Andrea Browne Taylor is an editor at Kiplinger's Personal Finance. .