So what exactly is a Walmart? If the rumours and intense speculation are correct - and that's a big if - and the world's largest retailer does make a bid to enter the Irish market, you will soon find out.

You may squeal with delight. Or you may see before you yet another sign of the End of Life as We Know It.

In the United States, Walmart was a term only vaguely recognised about 10 or 15 years ago, unless one lived in the mid-west or the south. Most people on either the east or west coasts had never set foot in a Walmart. From what we understood, and information was sketchy, it was some kind of massive, bigger-than-anything-you've-ever-seen-before kind of store where you could buy anything, cheap.

But there was a small-town-weird notion about the place. They had employees wearing yellow Happy Face stickers greeting you at the door. If you asked where to find a box of cat food, one of these maniacally cheerful drones would escort you to the aisle, hand you the box, and insist that you have a "nice day".

It all seemed a little creepy.

But as Walmart expanded well beyond its home base in Bentonville, Arkansas, something happened. Most Americans, even the coastal dwellers, somehow found themselves one fine afternoon inside a Walmart, somewhere. And life was never the same.

You walk in and immediately stop and stare. This is big, about an average of 220,000 sq.ft. or a space into which you could fit five British Tescos. The aisles look like the M1. It's bright, sparkling clean, happy music is playing, and someone soon chirps, "Hi, Welcome to Walmart". You scurry away, uncertain of this experience.

But then you start looking at the shelves. Look at those prices: A good quality white T-shirt is 99 cents; a pair of brand-name blue jeans is $13.99, around £10. This stuff is not junk, and it's cheaper than anywhere else.

In addition, there is almost nothing you cannot buy here. If it is possible to put any kind of price tag on your desired item, it probably is sold at Walmart. Combine a hardware store, grocery store, home goods, curtains, computers, furniture, spectacles, prescription drugs, televisions and tyres . . . It is all here.

THE conversion is complete. You feel shameful for your earlier bad attitude to Walmart. But you didn't know, you hadn't seen. Now, that your soul has been touched, your wallet transformed, you will worship forever at Walmart. In practical terms, you will drive out of your way to shop here.

Sam Walton knew you would feel this way eventually.

Born in Missouri in 1918, the son of a loan officer who repossessed farms devastated by nature and poverty or both, Sam Walton grew up poor and promised himself a different life. When he married in 1943, he borrowed the grand sum of $25,000 from his father-in-law to open his first small store. He became a student of retailing. All family holidays included visits to stores.

By the time he was in his 40s, Walton was a well-to-do merchant with 15 small stores in Missouri and Arkansas. But when a barber named Herb Gibson opened a then-controversial store in Berrysville, Arkansas, Walton saw the future.

What was controversial about Gibson's store, and it is difficult to imagine this now, was that it was a discount store, with lower prices than the competition. The idea threatened manufacturers' control of the marketplace and, obviously, other retailers were not thrilled. Many states even banned the practice.

But Walton grew committed to the concept of selling at the lowest possible price. By cutting margins to the bone, he developed an idea that any area where there were at least 4,500 people would support a discount store.

In 1962, he opened his first Walmart in Arkansas. People could be persuaded to travel a bit if the prices were right. Soon he was buzzing over towns in his low-flying airplane, getting the look of the land. By triangulating the proper intersection between several towns, he would decide the next Walmart location, which usually involved the purchase of several acres of farmland.

In 1985, Fortune magazine named Sam Walton the richest man in America. His wealth couldn't discount illness, of course, and he died of cancer in 1992. But his family - three sons, a daughter, and his widow Helen - still control a significant portion of the company. Their combined fortune is estimated at $32 billion. Today, Walmart is the largest retailer in the world. As of September 30th, 1999, there were 2,924 stores, Supercentres, or Sam's Clubs in the United States, in all employing 850,000 Americans. An aggressive international expansion plan launched four years ago has added an additional 220,000 employees around the world.

It has been through computerising that Walmart has succeeded in cutting prices. Its computer database is second only to the Pentagon's in capacity.

An aggressive international expansion plan - the company has invested $2 billion - has brought Walmart to most corners of the world. There are 145 stores in Mexico, five in Brazil, and two in China. But one of the most ambitious expansions has been into Europe, where Walmart arrived two years ago with its opening in Germany, where it now has 95 stores. In Britain, where Walmart took over Asda earlier this year, it now controls 229 stores.

EXPANSION is not without its difficulties. In Germany, Walmart's dog food manufacturer re-labelled the dog food cans, replacing a picture of Walton's English setter with a terrier after local management explained that setters were not popular. In China, it took Walmart a while to manufacture fermented bean curd.

Moreover, the very concept is anathema in some parts of Europe, even as it is in parts of the United States. An anti-Walmart US group called Sprawlbusters has grown and has successfully kept the retailer out of some communities. Without question, smaller stores cannot compete with Walmart and often close. Many labour unions also hate Walmart for what they say are strenuous working conditions.

In his book Made in America, Sam Walton wrote: "We're all working together; that's the secret. And we'll lower the cost of living for everyone, not just in America, but we'll give the world an opportunity to see what it's like to save and have a better lifestyle, a better life for all. We're proud of what we've accomplished; we've just begun."

Sounds pretty imperialistic. Coming soon to a town near you?