What is private browsing (Incognito, InPrivate, etc) and which browser is best at it?

When you want to hide something that you do online, you use a private browsing mode like Incognito from Google Chrome or InPrivate from Internet Explorer and Microsoft Edge. But, do you know how private you are when using this way of browsing? Can others still see what you are doing online? Also, do you know which browser is best at protecting your privacy? If you want to know the real answer to all these questions, read this article:

What is private browsing? What does it do?

Private browsing is a slightly more private way of browsing the web, compared to standard web browsing. In all the major web browsers, private browsing does the following things:

  • Deletes stored cookies from your browsing sessions, when closing private browsing. This means that if you have logged into Facebook, Gmail, YouTube or some other website, when closing all the private browsing tabs and windows, these cookies are deleted, and you are automatically signed out. If someone else tries to visit the same websites in a new browsing window, they will not be automatically logged in with your account(s). Cookies from non-private browsing sessions remain as they are.
  • Deletes the data you type in forms, like sign-up pages or login pages. When browsing the web, you may need to enter data into all kinds of forms, manually. When closing all the private browsing tabs and windows, this data is deleted and cannot be reused by anyone.
  • Deletes temporary files and cache from your browsing session. When you visit a website, files get downloaded to your computer or device, like images, styling files and so on. All these files are stored on your computer for the duration of your private browsing session, to make browsing faster. However, when you close all the private browsing tabs and windows, these files are deleted, so that they cannot be accessed and used by anyone else who knows where to look for them on the disk.
  • Deletes the browsing history from your browsing session. When browsing the web normally, the web browser stores a log of everything you have visited, so that you can access this information later or to autocomplete addresses when you type them in the address bar. When browsing privately, the browsing history from your session gets automatically deleted when you close all the private browsing tabs and windows. This way, other people with access to the same computer or device, cannot know what you have visited on the web.
  • Dos not store the search history from your browsing session. In modern browsers, you can search the web straight from their address bar. You type search keywords, press Enter and they are sent automatically to the default search engine to return results. In normal browsing sessions, this data is stored for later reuse, so that you browse the web faster. In private browsing, this data is not stored at all, so that it cannot be reused by others with access to the same computer or device.

All these things are great features that enhance a bit your privacy and confidentiality. They are useful to protect yourself from other people who have access to the same computer so that they don't know what you are doing online. However, private browsing does not mean that you cannot be tracked by anyone.

What private browsing does not do

Unfortunately, private browsing is not a silver bullet, and some entities can still track you, depending on the web browser that you are using and how it is set up:

  • The files you download and the bookmarks you save remain where you saved them. You need to delete them manually, if you do not want others to see them or use them.
  • You are not protected from keyloggers and spyware. Even though the browser deletes the data that you type, keyloggers and spyware act as independent programs that intercept all keystrokes. To protect yourself from these threats, you need a good antivirus.
  • Your internet service provider knows everything that you have done online unless you use VPN alongside private browsing, to encrypt your traffic. Fortunately, some browsers offer this kind of protection in their private browsing mode. Read on to learn more.
  • If you are in an organization like a corporation, or a school, your web browser communicates with a proxy server and/or a Domain Name Server that is managed by that organization. This means that IT administrator(s) log your activity online and they know what websites you have browsed. To protect yourself, you need a VPN to go along with private browsing. Luckily, there are browsers which offer VPN protection built-in.
  • The websites that you visit know that you visited them. However, if you also log into those sites, they will know exactly that it was you and what you have done while visiting them. If you don't log in, they will know that they have a visitor. Some websites might even identify you, through more advanced tracking, which leads us to the next point.
  • Ad networks know what you visited and what you searched for. Ad networks use advanced tracking techniques that track your browsing data across multiple sites, using your IP address, browser identifier, and cookies. Some browsers offer tracking protection or at least ad blocking features in private browsing. If you enable them, it will be harder for ad networks to track you. Enable a VPN connection too, and your private browsing will become a lot more difficult to track.

The web browsers we used for comparison and the add-ons we installed

For our comparison of private browsing modes, we used the following browsers for Windows: Google Chrome version 62, Internet Explorer version 11, Mozilla Firefox version 57, Microsoft Edge version 41, and Opera 49. We also installed the Pocket and LastPass extensions, the AVG Secure Search and Yahoo! toolbars, to see whether they are active in private browsing, and track user behavior. Some browsers like Opera and Microsoft Edge did not get the two toolbars because they do not work in them. Also, Mozilla Firefox did not get the AVG Secure Search toolbar because this toolbar is not compatible with the latest version of Firefox. However, Yahoo! did work.

What is the best browser for private browsing?

We tested each browser individually, and double checked that they do what they promise to do. We also verified the following:

  • Do they allow you to recover a closed tab when private browsing? This is a negative feature because you may forget one private tab open and someone else can come to the same PC and restore all your closed tabs, to see what you have visited.
  • Do they disable add-ons and toolbars? If a browser doesn't disable them while private browsing, you can be tracked by the add-ons that are installed. This is another important negative, especially when using browsers that have nasty toolbars and dodgy add-ons installed, like those from public places.
  • Do they block advertising and other types of tracking? Advertising networks have the habit of tracking users across multiple websites, to know what they want and serve ads that are more likely to get clicked.
  • Do they offer built-in VPN connections? This feature is useful when you do not want other organizations to know what you are doing online. When using VPN, your browsing is encrypted, and your internet service provider doesn't know what you are visiting, and neither does the organization on whose network you are on. Even advertisements will be misled into thinking that you are someone else.

Below you can see a comparison of all the features that are offered in the default versions of each browser. Some Yes boxes colored in green while others are colored in red. We used red and green to signal whether a feature or the lack of it, is a positive or a negative.

As you can see in this table, the best browser for private browsing is… Opera! It is not Google Chrome, while Mozilla Firefox is one of the worst offenders, even though it boasts about it offering "the most powerful private browsing mode with added tracking protection."

Let's discuss each browser, one by one and see what they offer and what they do not.

Google Chrome covers all privacy basics, and that's it!

When it comes to private browsing, the Incognito mode from Google Chrome offers only the basics. It can protect you from other people using the same computer knowing what you are doing online, and that is it. It does not protect you against anything else.

Internet Explorer can offer tracking protection and ad blocking if you configure it manually

Internet Explorer is an old browser, and most people make fun of it. You wouldn't expect it to perform decently, would you? We were surprised to see that you can get tracking protection in Internet Explorer as you do in Firefox. However, the catch is that it is not enabled by default and, once enabled, you need to configure it manually, like this: Set Up your Own AdBlock in Internet Explorer. Another issue with it is that it allows users to reopen closed tabs, even in its InPrivate browsing mode.

Therefore, if you forget one InPrivate tab open, someone else can restore your closed tabs and learn what you were doing online.

Microsoft Edge is just as private as Google Chrome

Microsoft Edge is another web browser that offers only the basics of private browsing: it protects you against other people using the same computer knowing what you do online. It doesn't protect you against anything else.

Mozilla Firefox is disappointing at private browsing

We discovered a surprising number of issues with Firefox's private browsing feature. First of all, it allows users to restore closed tabs, even when browsing privately. If you forget one private browsing tab open, someone else can restore your closed tabs and learn what you were doing online.

Another issue and this is more serious, is that it allows all extensions to run in private browsing. If you have a dodgy extension installed, it can track you with ease.

Mozilla Firefox should learn from other web browsers and stop enabling extensions while private browsing.

Opera is the best at private browsing if you turn on two built-in features

Opera was a refreshing surprise, and it has built-in features that place it above all others when it comes to private browsing. But, you need to enable its best privacy features manually.

First of all, when you open a basic private browsing window, it offers the same level of protection as Google Chrome and Microsoft Edge. But, you also get a VPN button on the left side of the address bar. Also, Opera encourages you in its description of private browsing to enable VPN. If you click the VPN button, you are automatically connected to Opera's best VPN server, depending on your location. This way, your ISP and the organization your computer's in, will not know what you are doing online. Also, advertisers will treat you like another user, from another location.

If you want ad blocking and tracking protection, you can get that too, because it is built into Opera. However, it is not turned on by default. Click or tap the big O button in the top-left corner and go to Settings. The very first setting is "Block ads." Check this box and choose tracking protection options that you want to use.

Once you do these two things, you get the most private browsing a web browser can offer, using only built-in tools and features.

We appreciate what Opera has to offer. However, other users may agree with us when we say that these two features should be enabled by default in Opera's private browsing mode.

NOTE: Some of you will say that Opera has an option to restore the last closed tab in its private browsing mode. However, if you use it, it doesn't open the last closed tab from private browsing but the last closed tab from normal browsing.

What if I do not want to switch to Opera or I cannot? How do I get the best private browsing mode?

We like how Opera has evolved in the last few years, and we consider it a great browser. If you want the best private browsing mode from a major web browser, you should install and use Opera. However, some of you may not be able to do this, for various reasons. For these users, we recommend the following:

  • Install and use a VPN service alongside your browser. We highly recommend Cyberghost and NordVPN.
  • Install a browser add-on like NoScript or AdBlock and allow it to run in your browser's private browsing mode (if the browser has such settings available).

What is your opinion about private browsing and what all browsers offer in this regard?

Now you know what private browsing is, what it does and what it doesn't do. You also have a comparison of the different private browsing modes that are offered by all the major web browsers. We are curious to know what is your view on this subject and what you think about our analysis. Comment below and let's discuss.