Q: While on Walmart’s website, I recently picked the closest store location. I share my neighbor’s wireless Internet signal. And now my neighbor sees the same Walmart store that I picked.

When I change the closest Walmart on my computer, it changes on his computer; when he changes the closest Walmart on his computer, it’s changed on mine.

I use Firefox, and I’ve turned on the options for privacy. I’ve told Firefox to delete all information except for passwords when I close the program.

How did Walmart retain my location preference and add it to my neighbor’s computer? And how do I make it so I can keep my store preference off his computer?

A: Location tracking is big business. Businesses want to target their advertising directly at nearby people — the very people most likely to visit their stores. So, when you visit a website, businesses make every effort to know exactly where and your wallet are located.

Walmart is probably employing two ways of tracking your location.

First, since you share your neighbor’s wireless Internet connection, you’re also sharing his IP address (Internet Protocol address) — the number assigned to your neighbor’s Internet account. Anybody can look up an IP address and link it to a particular city, so Walmart’s website probably does the same. Websites won’t know your name or exact address, but they can easily know your city and country.

To see IP address location tracking in action, head to www.whatsmyipaddress.com.

Second, you and your neighbor share the same wireless network name. Known as a SSID (Service Set IDentifier), it’s the name you see on your computer when you select a wireless network.

It’s no secret that companies track the names and locations of wireless network SSIDs. Since a wireless signal rarely spreads far from its source, its name can pinpoint your location to within a few hundred feet. Some companies hire cars to drive every street, logging the names and locations of every wireless network they find.

And nearly everyone with a “smart” cell phone helps create a database of SSID locations, as well. The smartphones sniff out wireless networks, sending the names and locations back to Google, Apple, and other companies to add to their databases. Cell phone owners benefit, because when Google and Apple know their exact location, they can find the closest coffee shops much more quickly.

Walmart’s website, when armed with this information, probably assumes that you’re both from the same family. After all, you both use the same IP address and the same wireless network name. And most families shop at the same Walmart store.

So, you’re not doing anything wrong with your web browser’s settings. And Walmart’s not identifying you personally, or your computer, or even your exact address.

When your neighbor visited Walmart’s website, the website checked its records, matched the wireless network name with the IP address. Since everything matched, Walmart probably assumed you were both from the same family and shopped at the same location.

After all, Walmart’s no stranger to location tracking. Walmart even tracks the clothes you wear.

In short, all the tracking is done on Walmart’s end, so your own computer’s settings have little effect. Walmart’s online privacy policy doesn’t dispute that it’s tracking customers’ locations by IP address and SSID. Its online privacy policy says Walmart “may collect technical information such as your internet protocol address.” The policy also says Walmart “may combine personal and non-personal information we collect online with offline information, including information from third parties.”

Walmart lets you opt out of some its information collecting by visiting its Privacy Preference Center. (You need a Walmart account to do that.) A visit to that center might offer some help. However, it may scare you when you see how much information large corporations gather. Walmart’s certainly not the only one doing this. Nearly all large businesses do some form of it, and location tracking grows more widespread each year.