"WHETHER I'M buying lunches or snacks, or gas or groceries or clothes, my purchases generate quite a paper trail, more for the vendor's benefit than for mine. "

When I was a child, I got the impression that people were supposed to save all the receipts they ever got, for tax purposes. Many children somehow obtain these sorts of delusions, along with misunderstanding the origin of babies or the nature of weather or traffic. (I myself confused Johnny Carson with Jimmy Carter until I was 10.)

For far too long, I persisted in holding on to my piles of useless paper. Maybe I thought they would prove something someday — an alibi, my frugality, or just my skill as an archivist. Maybe I didn't want to burn them, for fear of fire and noxious fumes. I was certain that those glossy thermal papers, if set aflame, would give off carcinogens and take days off my life.

But surely just tossing them would invite some vaguely imagined stalker to discover my candy-purchasing habits!

What was to be done?

The advent of the personal crosscut shredder has eased many worries for me. Unless I truly need receipts for returns, reimbursement or the like, receipts go into my private abyss.

There are many receipts that I now feed into the noisy jaws of my iron giant. Rough, curling paper carries faded purple numbers from an adding machine at a thrift shop. A tiny, shiny white slip from an Indian grocery store reveals extraordinary computing power in the shadows, spacing and typeface of the words "Thank you," yet lists all purchases only as amounts charged against "DEPT01."

(When I was at UC Berkeley, a sushi restaurant near campus went a step beyond the ritual "thank you" on its receipts. The bottom of each receipt read, "God bless you!" After the Sept. 11 terrorist attacks, it switched to, "God bless America!" I wonder whether it was ever switched back.)

And then there are the automatically itemized wonders that bureaucrats of earlier eras would have killed and died for. Thanks to Universal Product Codes, scanners, computerized registers and printers, a receipt from a convenience store reports on my four-item transaction in minute detail. I feel admiration and guilt toward the designers of this system, as my breakfast burrito does not deserve such an elaborate certificate of purchase.

But some stores really should include purchase details in their receipts. I would include, in this category, jewelry stores. A few years ago, as my boyfriend was cleaning his room, I saw a receipt on the floor. It was a record of an unspecified $300 purchase from a jewelry store. I picked it up, trying not to speculate and failing. My boyfriend looked up and saw my reaction. He quickly explained that this jewelry store had also branched out into cell phones, and that the latter genre of product was the reason for the receipt. I was amused and relieved and bewildered that the store's receipts were so nonspecific.

My grocery receipt leaves no doubt that I bought one box of mushroom bites @$5.39ea. His told me only that a $300 payment had been made and that some good or service had been rendered in return. From this, I extrapolate that when you buy something that costs millions of dollars, there are no receipts, only subtle nods.

No evidence to shred.

They didn't need shredders thousands of years ago. If someone took the time and effort to put paper and ink together, it was worth saving. Now, my everyday existence generates hundreds of records. Security cameras film me, telephone companies and e-mail servers keep track of my partners in conversation, PG&E notes my energy usage, and so on.

It is possible to log something, and it benefits someone to do it, and so it is done, in all these myriad ways. And if someone put her mind to it, she could correlate all these records to get a sense of me, a shell or a skeleton, depicting what I ate and borrowed and bought, the contours of my signature.

I leave a paper trail and wonder who will follow and whether they will find me.

Sumana Harihareswara writes each week for Bay Area Living. You can respond at sumana@crummy.com.