Tor Browser uses several techniques that help to prevent the linking of sessions. These include

• Tor Browser forces cookies to be discarded at the end of the browsing session. Cookies are small pieces of data that websites use to keep notes on who you are. They are commonly used as a login token, or as an identifier for adveritsment companies to track you across multiple sites. By discarding all cookies when you start a new browsing session, these cannot be used to track you across sites.

• Tor Browser changes the User-Agent to be generic - the same as all other people using TorBrowser. A USer Agent is a piece of text that the Browser constructs and sends, that contains system information. A website might use this for adjusting content that is sent to you - such as to match your language settings, or to work around browser rendering bugs. An example of a string is Mozilla/5.0 (iPad; U; CPU OS 3_2_1 like Mac OS X; en-us) AppleWebKit/531.21.10 (KHTML, like Gecko) Mobile/7B405 which contains both the language setting, as well as the versions of the Operating System and Web Browser. By changing the User Agent to be generic all Tor Browser users appear to be using the same browser, on the same operating system. This prevents another method of session linking.

• Tor Browser disables the Flash plugin, which has its own form of persistent storage. As Flash applets auto-load on most systems, this again prevents a method of tracking you across sessions.

• A similar story applies for HTML5 storage capability. Websites can store data on your machine with the use of HTML5. This data can be much larger and more varied than cookies, and is technically distinct; but the risks in terms of being used as a tracking mechanism are the same.

Tor Browser uses several techniques that help to prevent the linking of sessions. These include

• Tor Browser forces cookies to be discarded at the end of the browsing session. Cookies are small pieces of data that websites use to keep notes on who you are. They are commonly used as a login token, or as an identifier for adveritsment companies to track you across multiple sites. By discarding all cookies when you start a new browsing session, these cannot be used to track you across sites.

• Tor Browser changes the User-Agent to be generic - the same as all other people using TorBrowser. A USer Agent is a piece of text that the Browser constructs and sends, that contains system information. A website might use this for adjusting content that is sent to you - such as to match your language settings, or to work around browser rendering bugs. An example of a string is Mozilla/5.0 (iPad; U; CPU OS 3_2_1 like Mac OS X; en-us) AppleWebKit/531.21.10 (KHTML, like Gecko) Mobile/7B405 which contains both the language setting, as well as the versions of the Operating System and Web Browser. By changing the User Agent to be generic all Tor Browser users appear to be using the same browser, on the same operating system. This prevents another method of session linking.

• Tor Browser disables the Flash plugin, which has its own form of persistent storage. As Flash applets auto-load on most systems, this again prevents a method of tracking you across sessions.

• A similar story applies for HTML5 storage capability. Websites can store data on your machine with the use of HTML5. This data can be much larger and more varied than cookies, and is technically distinct; but the risks in terms of being used as a tracking mechanism are the same.

For further changes to Firefox, be it patches or changed settings have a look at the design documents of TorButton and TorBrowser

TorBrowser forces cookies to be discarded at the end of the browsing session. It also changes the User-Agent to be generic - the same as all other people using TorBrowser. This means all users appear to be using the same browser, on the same operating system. This prevents another method of session linking.

Tor Browser uses several techniques that help to prevent the linking of sessions. These include

• Tor Browser forces cookies to be discarded at the end of the browsing session. Cookies are small pieces of data that websites use to keep notes on who you are. They are commonly used as a login token, or as an identifier for adveritsment companies to track you across multiple sites. By discarding all cookies when you start a new browsing session, these cannot be used to track you across sites.

• Tor Browser changes the User-Agent to be generic - the same as all other people using TorBrowser. A USer Agent is a piece of text that the Browser constructs and sends, that contains system information. A website might use this for adjusting content that is sent to you - such as to match your language settings, or to work around browser rendering bugs. An example of a string is Mozilla/5.0 (iPad; U; CPU OS 3_2_1 like Mac OS X; en-us) AppleWebKit/531.21.10 (KHTML, like Gecko) Mobile/7B405 which contains both the language setting, as well as the versions of the Operating System and Web Browser. By changing the User Agent to be generic all Tor Browser users appear to be using the same browser, on the same operating system. This prevents another method of session linking.

• Tor Browser disables the Flash plugin, which has its own form of persistent storage. As Flash applets auto-load on most systems, this again prevents a method of tracking you across sessions.

• A similar story applies for HTML5 storage capability. Websites can store data on your machine with the use of HTML5. This data can be much larger and more varied than cookies, and is technically distinct; but the risks in terms of being used as a tracking mechanism are the same.