These days, companies aren't just making money on what you buy, but on how you pay for it - and it has spawned a whole new business: the payments industry.
Much of the discussion from the industry is about newfangled, high-technology ways to pay for stuff: There are credit cards and debit cards, smart cards and Internet commerce. Occasionally, there is still some talk of cash, but checks are definitely discouraged.
So is there any place left for the old, cautious traveler's check?
You would think not - but despite all the competition, Americans continue to buy more traveler's checks each year. That may be because there are more travelers.
"Honestly, they are not as popular as they were five years ago, but we have seen some slight growth because we have more members," said Beverly Hubbard, director of travel services/support at the American Automobile Association in the Mid-Atlantic Region. AAA is one of the largest merchants of American Express traveler's checks in the country.
Ms. Hubbard said some characteristics still strongly recommend traveler's checks.
"ATMs are only open at certain times, and people get mugged at ATMs all the time," she said. "The thing we always remind our customers is that your purchase (of traveler's checks) is insured."
And that insurance policy apparently still has some appeal; American Express, the world's largest merchant of traveler's checks, sold more than $26 billion worth of them last year, up more than 11 percent from 1991.
"We are very committed to this product," said Victoria Handwerk, an American Express spokeswoman.
Citicorp and Thomas Cook, the travel agency, remain the two biggest rivals to American Express as issuers.
While traveler's checks may never be as essential as they were in the era before credit cards and global ATM access, there are some realities that still make them attractive.
"I think they are definitely better and safer than cash, and not everybody has a credit card," said Diane A. James, an assistant manager at Ejay Travel in Philadelphia. "A lot of young people have to take traveler's checks (on trips) because they don't have credit cards."
Ms. James said that the checks now are used essentially for foreign travel, even though it is possible to get Greek drachma or Hungarian forints out of a cash machine in Athens or Budapest with the same ATM card you use at the mall at home. "Americans are not real comfortable with that," she said.
But the economy is strong, and Americans are traveling more than ever - so they continue to buy traveler's checks, Ms. Hendwerk said.
Despite their considerable usage, however, it is hard to imagine that they will be able to compete long into the future.
"I haven't heard tell of traveler's checks in a long time," said Norma Pratt, president and chief executive of Rodgers Travel, a 50-year-old Philadelphia agency. "Now it's all credit cards, and there is nowhere where you can't find an ATM," she said.
As recently as seven or eight years ago, Ms. Pratt said, people would pay for airline tickets with traveler's checks.
"You used to see them all the time," Ms. Pratt said. Today, she said, the convenience of the credit cards and ATM cards and the other attractions of the cards make them a favored form of payment.
"You get about 30-45 days to pay. That's a big advantage right there, and there are extra services - car rental insurance, extra flight insurance," Ms. Pratt said.
Moreover, no one gets mileage points for spending traveler's checks.
On the other hand: "If you lose the checks, you can get them replaced," said Ms. James.
That's better than cash, even if it comes out of an ATM.