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When I visit a website it sometimes puts cookies on my browser. Usually cookies keep track of browsing info from that particular site. If I don't delete those cookies and browse other websites, will the cookies be able to know which site I am browsing? Also, can any website read browsing history which is saved by browsers? Can any website know about my browsing history by help of cookies, browsing histories saved by browsers, or by any scripting language e.g. javascript?

Web_Designer
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Fsalad
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3 Answers3

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The short answer is yes, though it is not as easy as you might think.

The browser stores cookies independently for each domain. That means that www.foo.com cannot access the cookies made by www.bar.com and vice versa.

The vulnerability (or loophole) is in included pages. Most advertisements come from a different domain than the page itself, so they create their own sets of cookies. When another site includes an ad from the same ad provider, they can read their own cookies created earlier and they know you visited that page earlier. This way they can only track you on sites that host their ads. This is the strategy Google uses to serve relevant ads.

Also Facebook and other social networks can do this because of their ubiquitous like, tweeet, pin etc. buttons, which are also included content.

There are some techniques and browser extensions that mitigate this. For example, Firefox has containers and enhanced tracking protection which does work to hinder tracking, but it also breaks some functionality.

matega
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A third-party cookie placed on your machine at one site can be detected at a later time by the third party, so your browsing history is to some extent public. There are both HTML and Flash cookies, so if you wish to remove them delete both types.

Browsers such as Firefox can be set to a "private" mode in which cookies are deleted at shutdown. Cookies can also be deleted by the browser or by free tool such as CCleaner. Deleting cookies may require you to log into sites which had opened automatically before.

DrMoishe Pippik
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First yes. Simply put, if you allow a site to save your cookies, they will often share them with other syndicated sites, so that when you go to other syndicated sites, you will be prioritized to show what you've searched for.

If you want to avoid this, there are three ways:

1.Use browser focused on privacy(eg: Private Browser). Using Private Browser will keep you from being tracked, and once you exit, all of your records and passwords will be erased by default, which is the most convenient method.

2.Turn on privacy mode of the normal browser(eg:Chrome,UC,Firefox). Main browsers generally have privacy mode, and you can usually find it directly from the menu or the bottom bar and turn on it. But some also reflect that these modes are not completely private.

3.Keep Clear Browsing history. It means that each time you exit the browser, you need to go to setting>clear data. It's relatively cumbersome.

claire xu
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