Information about cookies used on uses cookies, small pieces of information placed on your computer's hard disk by web browsers. These fall into two categories:

  • Cookies created by pages within
    - these are used to help the pages work, e.g. by remembering your login name in SudokuXP

  • Cookies created by Google Ads
    - these are used by Google to track your browsing, and deliver tailored ads to you. Click here to jump to more details, including links to tools for preventing Google from doing this.

Cookies created by pages within

Cookies created by are used to make the pages work, e.g. to store usernames so the pages can display them. We don't track your path through the site, measure how long you stay, or anything like that. We don't share any information stored in cookies with anyone else either.

Web browsers keep cookies from different domains (e.g., separate, so other websites can't read the data in cookies created by However, we can't guarantee that viruses or other malware won't be able to break a browser's security system and read the cookies it's stored - this is beyond our control.

Here's a list of sections that use cookies, with details of what they use them for (please note that it may not be exhaustive - there is some quite old stuff in odd corners of the site!)


Sudoku XP

Sudoku XP
When you log into Sudoku XP, it creates a cookie containing your username (but not password) plus any settings you've saved by clicking the 'Save Settings' button. This is a session cookie, i.e. it's removed from your computer when you close your browser, reboot your computer or log out of Sudoku XP.

Please note that if you disable cookies in your browser, then you won't be able to log in to SudokuXP.


Client-Server quiz.
If you do well in one of our online quizzes (try them!) you're offered the chance of putting your name onto the leaderboard. If you do, the name and location you type in (e.g. "BrightSpark", "London") are stored in a cookie on your computer for up to a year. This is so that the quiz system can recognise you if you return to play more quizzes. You can remove the cookie via a link from the 'add to leaderboard' page (you'll have to play another quiz to get there!).


Paul's Backgammon Vaults.
When you first replay a backgammon game, the system checks the speed of your computer's display in order to make the piece moving animation as smooth as possible. It stores this value (a number) in a cookie, which remains on your computer for up to a year.



Housemates Dilemma, Avalaff, Avalaff Sig Buffle.
These games all create cookies to store your username, if you choose to enter one. The cookies remain on your computer for up to a year, and are used to remember you when you play the game again.


Paul's Web Design Pages
The section on my client side cookie libraries uses cookies to demonstrate the libraries' management of cookies! The cookies just store whatever text you type into an on-screen box.


Can I stop these cookies from being written by

Yes - by disabling cookies in your browser (see your browser's help pages for details of how to do this). However if you disable cookies then the functionality supported by them (e.g. remembering your name in Avalaff and Housemates Dilemma) won't work. SudokuXP, which uses a 'logged in' cookie to verify that you're a member and have successfully logged in, won't work at all with cookies disabled.


Cookies created by Google.

Some pages within carry adverts supplied by Google, like this one:

Example of Google Ad

These adverts place their own cookies on your computer, which Google uses in conjuction with information gleaned from Google searches you've made, and other sources such as websites you've visited, to send ads which it thinks will be of interest to you. For example the ad above was sent to me because I'd searched for that product's name in Google a few days earlier.

For full details of Google's use of cookies, including ways to manage them, click here.


More information on cookies.

To learn more about cookies and how to control them, visit

If you live in the EU, then this page has a guide to online behavioural advertising and online privacy.

If you live in the USA, this page has information about opting out of behavioural advertising.