__cfduid on www.telegraph.co.uk
About this cookie:
Cookie associated with sites using CloudFlare, used to speed up page load times. According to CloudFlare it is used to override any security restrictions based on the IP address the visitor is coming from. It does not contain any user identification information.
There is no specific information about this cookie from this host provider. If you have any information about how this cookie is used by this host, please get in touch.
About this cookie’s host: This domain is owned by US company Roxr Software, and it used for the provision of web analytics services for site owners.
Related general information about __cfduid:
These cookies collect information about how visitors use a website, for instance which pages visitors go to most often, and if they get error messages from web pages. These cookies don’t collect information that identifies a visitor. All information these cookies collect is aggregated and therefore anonymous. It is only used to improve how a website works.More about cookie classifications.
Third Party Cookies
If the host domain for a cookie is different to the one in the browser bar when it was downloaded, then it is a third party cookie.
They are usually placed in a website via scripts or tags added into the web page. Sometimes these scripts will also bring additional functionality to the site, such as enabling content to be shared via social networks.
For example, if you visit a site that has a YouTube video in one of its pages. This has been included by the website owner, using a piece of code provided by YouTube. YouTube will then be able to set cookies through this code, and know that you have watched that video, or even just visited the page the video is in.
Online advertising is the most common use of third party cookies. By adding their tags to a page, which may or may not display adverts, advertisers can track a user (or their device) across many of the websites they visit.
This allows them to build up a 'behavioural profile' of the user, which can then be used to target them with online ads based around their 'calculated' interests.
Analytics cookies are probably the most common form of persistent cookies in use today.