SID on www.tracker.co.uk
About this cookie:
This is a very common cookie name but where it is found as a session cookie it is likely to be used as for session state management.
This cookie is used by Google in combination with HSID to verify a Google user account and most recent login time.
About this cookie’s host: YouTube is a Google owned platform for hosting and sharing videos. YouTube collects user data through videos embedded in websites, which is aggregated with profile data from other Google services in order to display targeted advertising to web visitors across a broad range of their own and other websites.
Related general information about SID:
These cookies are used to deliver adverts more relevant to you and your interests. They are also used to limit the number of times you see an advertisement as well as help measure the effectiveness of the advertising campaign. They are usually placed by advertising networks with the website operator's permission. They remember that you have visited a website and this information is shared with other organisations such as advertisers. Quite often targeting or advertising cookies will be linked to site functionality provided by the other organisation.More about cookie classifications.
Third Party Cookies
Session Cookies are only stored temporarily in the browser's memory, and are destroyed when it is closed down, although they will survive navigating away from the website they came from.
If you have to login to a website every time you open your browser and visit it - then it is using a session cookie to store your login credentials.
Many websites use session cookies for essential site functions, and to make sure pages are sent to the browser as quickly and efficiently as possible.