If you have a Gmail account, Google has been keeping track of all your purchases, or at least all the ones that generated an email receipt. You can find them all grouped in one place on a "Purchases" page for your account. Here's a link: myaccount.google.com/purchases.

CNBC first reported on the tracking, which, like so many things concerning personal information, seems highly useful and somewhat creepy at the same time. Google told CNBC--and has posted on the Purchases page--that only users can see their own purchase information. It also says that Google won't sell the information or use it to choose which ads you see. 

Google hasn't said why it's keeping track of users' purchase information, but there are some pretty obvious reasons for the company to create algorithms that recognize which emails contain purchase information. Ask the Google Assistant (or a Google Home device) "Hey Google, where's my package?" and it will look in your email to try and find the answer. That helps it compete with Amazon's Alexa, which provides purchase and package delivery information for Amazon packages.

And having a record of all your purchases in one place is certainly very convenient. The Purchases page keeps track of subscriptions too--when I looked at mine, I was reminded that I had bought a subscription to Weather Underground that automatically renews every year, something I'd completely forgotten.

Deleting your purchases could take a while.

There's some bad news for people who find this tracking of their buying concerning and see it as encroaching on their privacy. You can delete items from your purchase history, but only by deleting the email that contains your receipt. If you're saving that email just in case you needed to return the item, you can't delete it from your Purchases page. 

You can only delete these items one at a time, which could make for a long and tedious process if you want to get rid of them all. A simpler approach might be to skip the Purchases page and delete the relevant emails directly in Gmail, which has sophisticated tools for finding specific types of emails. It appears that once you delete an email containing a receipt, that item disappears from the Purchases page automatically. I discovered this accidentally: To save storage, I've deleted all my emails before 2015, and my Purchases page only goes back as far as that year.

Google also told CNBC you can turn off this feature if you want to, although CNBC reporters wrote that when they tried to do that it didn't work. But perhaps "tracking" is the wrong word for what Google is doing here. Rather than follow you around the Web, the company is using algorithms to parse email messages and identify and analyze those that contain buying data. Which means, in a sense, that Google is "reading" your emails, something that would make some people very uncomfortable.

It wouldn't be the first time, though. From the beginning, Gmail deployed algorithms that analyzed the text of your emails and used it to choose ads to show you. It ended that practice in 2017 because it made corporate customers leery of Google. I was happy about the change. A friend of mine is the author of a book about the horror movie industry. Her book title includes the word "cockroaches"; the title is mentioned in her automatic email signature, and so emails from her used to come with ads for pest control.

Some users will certainly see the Purchases page as one more blow to user privacy, while others may find it a convenient way to review what they've bought. It could be a lot more convenient, though, if Google also included purchases made with Google Pay or the Google Wallet. It's odd that these items aren't included since obviously Google knows about them.

It's also odd that we needed CNBC to tell us about the Purchases page. From what a Google representative told CNBC, the company views it as an added feature. "To help you easily view and keep track of your purchases, bookings, and subscriptions in one place, we've created a private destination that can only be seen by you," the representative said. But if that's true, why wasn't Google the one to tell us about it?