As much as I dislike the big, blood-sucking banks, I've got to give them credit for doing some things extremely well. I got a call last night from the fraud division of my mega-bank (interrupting "Honey Boo-Boo"). After a little back and forth to verify that the woman on the phone was really from the bank, she said she was calling about strange activity on my credit card. Their computer system tracks purchasing trends and patterns, and a charge tripped the alarm because it didn't fit the pattern. She was right. Somebody in Vietnam was trying to run a $6 charge through. If that had cleared without a problem, the next move would have been to go hog wild and run it up to the max.

While Vietnam is well outside the "pattern" on my account, the idea that there is a pattern to my spending is sort of surprising. I tend to run almost everything through the credit card (and pay it off every month), so there are all the normal grocery store, gas station, restaurant charges. Finding a pattern there is pretty easy. Draw a 50-mile circle around my house, and anything in there seems reasonable.

But then there is the other stuff. I buy a fair amount of stuff online, and it's not unusual to have online charges for antique tractor parts in several different states on the same day when I've got a project going. When the lady from the bank started reviewing the last month's activity on the card to get me to either say it was legit or not, the lack of a pattern came pretty clear. Steiner Tractor Parts in Michigan, All States Ag Supply in Iowa, Farmall Parts in Oregon, Miller Tire in Nebraska - scattered all over the country, though I suppose at least clustered around one type of purchase. Except for the bicycle parts.

On the day the bank's computer choked on my account, I had just purchased a new mountain bike. That purchase would have stood out just because it was bigger than usual, though it was at least close to home. But the number of the bank's customers who are chasing carburetor parts for a 70-year old John Deere, a new 29-er mountain bike, and telemark ski gear in the same billing cycle is probably rather small. That alone ought to have at least triggered the alarm for a high level of eccentricity, even if there isn't anything fraudulent in there. The guys with in the white coats with the big butterfly net may be stopping by any time.

Some months there won't be more than a few groceries and a tank of gas on the credit card. Other months there are bicycles or chainsaws that really run it up. Somehow, their computer has determined that there is a "pattern" in my life, even if I can't predict my own spending. But $6 from Vietnam set things off.

I've got no idea how the account information found its way to the other side of the world. When you think about it, your credit-card number gets scattered far and wide. I never leave it on file with the various vendors I deal with, but for every online purchase, the card information is sent out there. Sometimes it's secure. Sometimes it's not as secure as we might think. There's no way of knowing whose system is leaking (iTunes? Amazon? the bank itself?). It seems improbable that somebody in Vietnam is hacking into the hardware store in Kamas. So it's nice to know that in the deep recesses of the bank, there is a system that is looking out for us, and when something abnormal happens, they are on it immediately. The charge went through at the bike shop without a problem. An hour later, it would have been declined.

It's a system that works largely on faith. We hand over a credit-card number and a shipping address, and the merchant accepts it as payment. I believe that the tractor parts will show up at my door, and they do. It's so smooth that I never give a moment's thought to what goes on behind the scenes. The quick action from the bank's fraud unit probably prevented a nightmare scenario of phony charges and messed-up credit. The old card was put out of its misery, and a new one will arrive in a couple of days. In the meantime, I'm reduced to cash, which has become something of an anachronism - making change seems so quaint. Coins? We still have coins?

Anyway, it pays to watch your accounts online so, if there is anything weird, you can call the bank. But chances are they will spot it before you do.

Tom Clyde practiced law in Park City for many years. He lives on a working ranch in Woodland and has been writing this column since 1986.