Betfair put over 40 Cookies on your PC when you first log on

no good for your wasteline but a generous gesture from BF imo

Onlooker what happens if yopu log-in with Mozilla but use IE for the rest of your buisness?

Same as if you log on top Betfair on Safari, and use   Firefox for the rest of your surfing.   

Perhaps best to use separate browsers - as you ask, and I do.

Also - Set ALL you browsers to BLOCK THIRD-PART COOKIES


Tracking

Tracking cookies may be used to track internet users' web browsing habits. This can also be done in part by using the IP address of the computer requesting the page or the referrer field of the HTTP header, but cookies allow for a greater precision. This can be done for example as follows:

   1. If the user requests a page of the site, but the request contains no cookie, the server presumes that this is the first page visited by the user; the server creates a random string and sends it as a cookie back to the browser together with the requested page;
   2. From this point on, the cookie will be automatically sent by the browser to the server every time a new page from the site is requested; the server sends the page as usual, but also stores the URL of the requested page, the date/time of the request, and the cookie in a log file.

By looking at the log file, it is then possible to find out which pages the user has visited and in what sequence. For example, if the log contains some requests done using the cookie id=abc, it can be determined that these requests all come from the same user. The URL and date/time stored with the cookie allows for finding out which pages the user has visited, and at what time.

Third-party cookies and Web bugs, explained below, also allow for tracking across multiple sites. Tracking within a site is typically used to produce usage statistics, while tracking across sites is typically used by advertising companies to produce anonymous user profiles (which are then used to determine what advertisements should be shown to the user).

A tracking cookie may potentially infringe upon the user's privacy but they can be easily removed. Current versions of popular web browsers include options to delete 'persistent' cookies when the application is closed.
[edit] Third-party cookies

When viewing a Web page, images or other objects contained within this page may reside on servers besides just the URL shown in your browser. While rendering the page, the browser downloads all these objects. Most modern websites that you view contain information from lots of different sources. For example, if you type www.domain.com into your browser, widgets and advertisements within this page are often served from a different domain source. While this information is being retrieved, some of these sources may set cookies in your browser. First-party cookies are cookies that are set by the same domain that is in your browser's address bar. Third-party cookies are cookies being set by one of these widgets or other inserts coming from a different domain.

Modern browsers, such as Mozilla Firefox, Internet Explorer and Opera, by default, allow third-party cookies, although users can change the settings to block them.
There is no inherent security risk of third-party cookies (they do not harm the user's computer) and they make lots of functionality of the web possible, however some internet users disable them because they can be used to track a user browsing from one website to another. This tracking is most often done by on-line advertising companies to assist in targeting advertisements. For example: Suppose a user visits www.domain1.com and an advertiser sets a cookie in the user's browser, and then the user later visits www.domain2.com. If the same company advertises on both sites, the advertiser knows that this particular user who is now viewing www.domain2.com also viewed www.domain1.com in the past and may avoid repeating advertisements. The advertiser does not know anything more about the user than that—they do not know the user's name or address or any other personal information (unless they obtain it from another source such as from the user or by reading another cookie).

Privacy and third-party cookies

Cookies have some important implications on the privacy and anonymity of Web users. While cookies are sent only to the server setting them or the server in the same Internet domain, a Web page may contain images or other components stored on servers in other domains. Cookies that are set during retrieval of these components are called third-party cookies. This includes cookies from unwanted pop-up ads.
In this fictional example, an advertising company has placed banners in two Web sites. Hosting the banner images on its servers and using third-party cookies, the advertising company is able to track the browsing of users across these two sites.

Advertising companies use third-party cookies to track a user across multiple sites. In particular, an advertising company can track a user across all pages where it has placed advertising images or web bugs. Knowledge of the pages visited by a user allows the advertisement company to target advertisement to the user's presumed preferences.

The possibility of building a profile of users is considered by some a potential privacy threat, especially when tracking is done across multiple domains using third-party cookies. For this reason, some countries have legislation about cookies.

Third-party cookies can be blocked by most browsers to increase privacy and reduce tracking by advertising and tracking companies without negatively affecting the user's Web experience.[27]  Many advertising operators have an opt-out option to behavioural advertising, with a generic cookie in the browser stopping behavioural advertising