Are you thinking of buying someone a Challenge as a gift? If so, please buy a Gift Card. Why? Whenever you purchase a Challenge through the Challenge Shop, a URN is generated that is specifically linked to you and your contact details, so only you will be able to request answers to clues or submit the final answer. If, however, you buy someone a Gift Card, they can choose whichever Challenge(s) they wish and when they redeem their voucher will be registered as a member in their own right. You can choose to have the voucher emailed to yourself, to print off and present in person. To elevate the gift, you can buy stylish Presentation Sleeves from our Challenge Shop for just £1. We'll post the Presentation Sleeve(s)s out for you to insert the Gift Cards you have purchased and present to your friends or loved ones. The perfect stocking filler or gift at any time of the year! All proceeds from the Presentation Sleeves will be donated to an animal and/or environmental charity. Alternatively, you can choose to have the Gift Card emailed directly to the recipient as an eGift Card, and pre-schedule whatever date you would like them to receive it. To give the Gift of Adventure, click here.

To redeem your gift card, go to Challenge Shop in the header and find the item(s) you wish to purchase. When you reach the final page of processing your order, 18 Clues Checkout, they click Redeem a gift card and carefully enter your unique gift card code.

Any amount left over after making a purchase can be used in future purchases. For example, if a customer has a £30 gift card and spends £15, they can use the remaining £15 in future when shopping on the 18 Clues site.

If the order total is more than the gift card balance, you can pay for the remaining cost using another payment method.

Walking Challenges: Before embarking on your first Walking Challenge, you will need to download the what3words (W3W) App onto your device. This is what you will use to guide you to each clue location. For each clue, simply enter the given W3W location into W3W and follow the directions. The clue will not always be exactly at the W3W location, but will always be very close by. Virtual Challenges: Access the W3W website on your PC or laptop. After entering the W3W three-word location, you will need to enter Google Street View so that you can look around for your clue. Google Street View works in tandem with W3W, so once you get the hang of it, you will find it easy to use. If you are new to W3W / Google Street View, please click through to 'W3W / Google Street View' under Customer Service in the 18 Clues website footer (www.18clues.co.uk/w3w-google-street-view).

What3words (W3W) is a geocodng system that divides the world into three metre squares and gives each one a unique three-word address. It is based in London, but is used all over the world to find, share and save precise locations. To learn more about W3W and how to use it, we have included a link under Customer Service in the website footer. We suggest you familiarise yourself with the contents of this link before you attempt your first Virtual Challenge.

Aside from location and backstory, the Walking and Virtual Challenges are quite different. All clues and the final solution in the Walking Challenge differ from those in the Virtual Challenge. So, many who are in a position to do the Walking Challenge also purchase the Virtual Challenge to complete at home.

The majority of clues are based on objects that are unlikely to disappear. However, occasionally clue material may be destroyed, obscured, removed or meddled with. We are soon alerted to such changes, and make amendments to our Challenges as quickly as we possibly can. Whenever a Challenge is updated, a new edition is published. The edition of your Challenge may be found at the base of the Solution Page in the Challenge booklet (in the right hand side of the URN box). To find the most recent edition of the same Challenge, select the Challenge on the website, select the Challenge version in the drop down menu at checkout, and you will see the current edition of that Challenge on the top right hand side of the Challenge image to the left - eg [e1]. If the edition number on your Challenge booklet is two or more less than the current edition, you may contact us here to request a PDF of the most up-to-date edition.

You can complete a Walking Challenge at any time, although we recommend that you start it early enough to reach the last clue during daylight hours. If possible, you may like to check in advance that there are no majer events taking place at the Challenge location that may impede your experience. Virtual Challenges may be undertaken at any time. You can complete them in one sitting, or in small spurts - whatever suits you best. There is no time limit to completing either Challenge, although if the current prize on offer is one that you are particularly interested in, you may like to make sure that you have submitted your answer before that prize draw expires. A new prize package comes into effect quarterly - ie every three months. For further details, see www.18clues.co.uk/prize_draw .

You may use our 'I've No Clue!' facility to request the answer to up to two clues. You can do this by clicking on 'I've No Clue' at the top right of the home page of our website and clicking on the relevant Unique Reference Number (located on the Solution Page in your Challenge booklet), plus the number of the clue you want help with. This facility is completely free of charge and we encourage you to use it to increase your chances of solving the Challenge and entering the prize draw.

Needless to say, we are unable to provide you with a full set of answers to a Challenge. However, you may request the answer to a maximum of two clues if you get stuck or if a clue has disappeared (see 'I've No Clue!'). Remember that your URN may only be used once to submit an answer. If you submit the incorrect answer, you will not be entered into the prize draw.

You know your pet best, so we will leave this to your discretion. It is vital, however, that you keep your precious pet on a lead, and safe. Remember to take plenty of 'poo' bags, and clean up after your dog as and when necessary.

Winners are notified by email within seven days of the prize draw, and their Unique Reference Number (URN) will be published on our website at the same time. For full Prize Draw Ts & Cs, please click here. Our prize draw 'quarters' run December - Feburary, March - May, June - August, and September - November. There will be a different prize package on offer in each quarter. Each new prize package commences at 00:01 on the first day of the new quarter (ie 1st March, 1st June, 1st September, and 1st December) and closes at 24:00 on the last day of the quarter (ie 28th/29th February, 31st May, 31st August and 30th November). The final day of the current Prize Draw may be found on the Home page.

You can only enter the prize draw once with each Challenge booklet and accompanying URN.

Our 18 Clues Challenges are currently only open to residents of the United Kingdom. For full details, please see the Prize Draw Ts & Cs.

All charities we support relate to animals, nature and the environment. Each Challenge is linked to a specific charity. Where we are able to name the charity a specific Challenge links to, we will do so. Some of the larger charities do not permit the use of their name until donations to their cause reach a certain threshold. We will, however, publish the names of all charities we donated to in the previous quarter on our website. This list will increase as new Challenges and therefore charities are added.