can using private windows make it hard for sites to target me with ads?
 

I bought something from an online retailer recently as a first-time purchase. Ever since then, to my annoyance, the company has periodically displayed its ads on certain other sites I visit. Not in any way that would constitute spam; nothing that other companies wouldn't do. I would say it's the same as an offline company pestering me after I do business there, except with those, I'm used to reputable retailers leaving me alone unless I signed some kind of guest form. It's the principle that annoys me--how did the company get the information necessary to follow me?
My first assumption was cookies, but I'm pretty sure I've deleted all the cookies the company left on my browser. (Although ti's difficult to be sure, because I noticed that many cookies use unhelpful names that don't identify whose they are, and I don't want to accidentally delete unrelated cookies.) I also can't be sure it wasn't more because Google tracked me (why not? it would), because I leave my Google e-mail open and the ads are appearing on Google-owned sites I visit.

Whether it was the retailer or Google, could I have avoided this by using a private window? I've been made aware that private windows are only so effective, with research showing many websites can defeat them, but...they're what we have. I've been aware of private windows but have never taken much advantage of them.

Why not just delete all your offline content? For paswords either write them down or use a password keeper.
It would be possible to target adverts based upon something like IP but this is likely just Google. Why do you allow Google to set cookies in the first place?
Also, uBlock and NoScript are worth a look - very rarely see adverts on my PCs.

Private may help. I use hosts file with those ad companies blocked.

welcome to the third millenium and the wonderful world of google-analytics, ad services & co.

never heard the story of online ads knowing you're gay / pregnant before you do?

this is the reason why so many people use noscript, adblock or requestpolicy addons. or /etc/hosts-based adblocking.

You, like all of us, have a browser fingerprint. https://panopticlick.eff.org/

'Incognito' or 'Private' browsing mode helps a little, because it discards cookies. However, there can be a lot of tracking happening aside from just cookies, so you still might be leaving a trail as you browse even in private mode.

First of all, install an ad-blocker or use /etc/hosts to block ads. It works wonders.

Secondly, I have found it better to create a "shopping profile". Open an email account specifically to use when signing into online stores and always use that email address. NEVER check that email address except in Private mode, and do NOT remail signed into that email address. When shopping, go into Private mode, sign into the email address, and do your online shopping. Once finished, lag out from everything and exit Private mode. This works pretty well for me, at least as far as I can tell.

I use this technique on my personal computers at home, and the results are that during normal browsing, sites appear to not know who I am or how to advertise to me. Once I go into Private mode and sign into my account, individual sites do target ads at me, but not across sites (for instance, just because I buy a graphics card at foo.com does not mean that I get GPU ads from bar.com).

Finally, for added value, use a user-agent switcher plugin. There are some good ones out there. I find that switching user-agents while shopping does a lot to confuse websites. It's amazing how many sites still rely on user-agent reporting to determine whether something works or not, much less who you are.

tl;dr: use Privacy Mode upside-down: do your public-facing browsing in Private mode, and do your daily normal stuff in normal mode, privately.

You are correct in thinking that cookies are used to track you from site to site. History is also used to track you. The way to eliminate the tracking is to periodically delete of all of your cookies and history.

I tried removing all cookies and history in several browsers. The ease of doing so varies from browser to browser. I found that the browser which defeats tracking best is qupzilla. I set up qupzilla so that when I close qupzilla it deletes all cookies and all history. At any time during a web session I can simply close and restart qupzilla and all that tracking annoyance is gone. qupzilla is fairly new and it is buggier than most of the other browsers but to me the convenience of eliminating tracking with two clicks outweighs the inconvience of hitting a qupzilla bug every other day or so.

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Steve Stites

The only particular reason I keep any cookies is because I don't want to bother re-entering every password at every visit to a site.

I like to use the cookie whitelisting in Firefox (seems to be the only browser with it) -- it takes a bit of setting up (for example this site requires cookies from thequestionnetwork.org) but you get make it so that, for example, this site remebers you but Google's services don't.
I have to admit to not setting it up on this phone yet though.

I would be disturbed (if not at all surprised) if Google is responsible for this, because the website I visited to buy something was not a Google-owned service, it was an online eyeglass retailer. But I had my Gmail accounts open in tabs--I always do. Did Google take advantage of that to track me by my cookies?

I never wanted to use Google again after I found out about their privacy theft within the last few years. Perhaps all the well-known free e-mail services do the same thing but...I don't necessarily hear about it. I went back to my Yahoo e-mail, but I abandoned it as my primary e-mail after Yahoo's horrendous security breach last fall.

almost every site nowadays makes cross-site requests, i.e. contacts some other domain (you can make this visible - and disable if so desired - with an addon like requestpolicy).
very often for the purpose of generating suitable advertising.
almost every site (even this one) has a request to googlesyndication.com, google-analytics.com, googleadservices.com etc.
amongst many other things, google is the top advertisment distributor on the internet.