Well now, this is interesting. A blog post from Mozilla today brings to light the habits of those using Private Browsing.
The feature, first introduced in Firefox 3.5, gives web browsers the option of browsing the web without keeping track of their history.
Some of the more interesting aspects (with my thoughts in bold) to come out of the Test Pilot study :
Activation spikes at lunch.

Though people switch into Private Browsing mode throughout the day, there are a few periods where activation surges:
- Lunch: users likely switch into Private Browsing during their lunch breaks. We see a major spike between 11 and 2pm.
(No surprise. No one wants their employer to know what they’re looking at during their lunch break.)
- After School / Work: users appear to switch on Private Browsing just after they’ve returned from work or school, which is around 5pm.
(Very interesting. Parents should take note of as children get home from school and switch to Private Browsing before their parents get home sometime around 5. One can only imagine what they’re doing on the web during that time. Lascivious pictures of Justin Bieber and/or Miley Cyrus anyone?)
- After Dinner: we have another substantial peak between nine and ten pm.
- Late Night: a minor spike exists an hour or two after midnight.
(These last two are almost to easy to comment on given that most Private Browsing takes place in a 10-minute window, outlined below. You can imagine what takes place in that brief amount of “private” time after dinner and late in to the night.)
The 10-minute window is the most common.

Now that we know when users jump into Private Browsing, the next question involves finding out how long users stay in it. The 25th percentile stays on for about 4 and a half minutes, the 75th percentile around 22 minutes, and the median stays in for about 10 minutes.
What one can glean from this information is that people like to have their “me” time, whatever you interpret that to be, and they keep it short and sweet.
All of this evidence points to one thing and one thing only. People enjoy browsing videos of cute cats in private, videos which last, on average, 10 minutes.

















If people think that private browsing at work stops their employer from seeing what they browse, they don’t understand how it works (nor does the author, or at least he doesn’t clarify in the article).
Whether you’re connecting to the internet via an ISP or your employer’s network, they still log everywhere you visit. Private browsing only kills your browser history while it’s turned on. It’s for keeping your browsing habits private if you are sharing your computer.
You spelled the word ‘too’ like the number, when you meant ‘also.’
I share your stance. Nothing is truly “private.” And thank you for the edit. Appreciate it, your reading of the article and insight!
Besides which, what good is ‘private browsing’ if Mozilla are monitoring it!?
In other offices, the system admin blocks websites that are most visited but during lunch breaks they unblock. Private browsing sometimes can be helpful but there are specific times that this can be a disadvantage.
I use private browsing when I have to login to my other facebook account. You don’t need to log out you current facebook in order to sign in to your other facebook. -GAR Labs