Most of the modern browsers (Chrome, Firefox, Opera) expose a so-called private mode that enables you browsing the web without leaving any traces of data on your computer. But is this mode really private? Learn about private browsing.
Firefox Private Browsing
Though it goes by different names in different browsers (InPrivate, Private Browsing, Incognito), the idea is the same; they keep your online journeys hidden by deleting or rejecting cookies, not tracking history, and emptying the cache when you quit.

The problem

Unfortunately, these tricks only solve part of the privacy equation, and dedicated snoops could still see what sites you’re visiting. Let take a look and see how these private browsing modes fail to truly cover your tracks, and how to better hide your browsing habits (for whatever reasons you might have).

Cached DNS Entries and Flash cookies

The big problems are the DNS cache and Flash cookies, neither of which are covered by browsers’ privacy controls. DNS, which is often described as the Internet equivalent of a phone book, translates Web site names (such as Switched.com) into IP addresses (e.g., 127.0.0.1). These IP addresses are saved locally to speed up access to those pages in the future. Private browsing modes don’t clear this cache, which means that somebody could tell what sites you’d been visiting just by looking at locally stored IP addresses, even if you’d cleared your browser history.

Flash-powered sites, like regular HTML Web sites, use cookies to track things such as whether you’re logged in, what videos you view, and other such useful information. (They can also be used to track what you do for nefarious purposes, but that’s not our concern today.) Sadly, while browsers’ privacy settings clear out the cookies that Web sites deposit, they leave Flash data alone. That means that everything from your viewed videos to Web sites will be clear as day to anyone who peeks in your Flash “#SharedObjects” folder.
Private Browsing Flash

Cleaning these things up is as easy as typing “ipconfig /flushdns” into the command prompt (or ‘Run’ box, whichever you prefer), and deleting the contents of “%appdata%\Macromedia\Flash Player\#SharedObjects“.

The Solution

The best solution is to install CCleaner and create your own batch file to run after your browsing session, to make sure your browser cache, Flash cookie cache, and DNS entries are cleaned out.  Just create a new plain text file and save it as a .bat file (e.g., browserclean.bat), then add the following to the file, noting that the /AUTO switch tells CCleaner to run silently.

“C:\Program Files\CCleaner\CCleaner.exe” /AUTO
ipconfig /flushdns

Once you’ve created the file and saved it into some useful location, you can create a shortcut on your desktop, quick launch bar, or pin it to your start menu.

Visit Lifehacker for a more in-depth look at how ‘private browsing’ modes fail.

Important! You have to remember that private mode does not hide your IP address, it only erases your browsing history!

>> Via Lifehacker.com & Switched