Earth Hour started in 2007 in Sydney, Australia when 2.2 million individuals and more than 2,000 businesses turned their lights off for one hour to take a stand against climate change.
Since then the event has grown and grown to become what it is today with millions of people and companies now participating in the dark hour of March.
Last year the event saw 128 countries and territories taking part making this a record, although that could be broken by the 2011 event which is bound to be the biggest to date.
In Scotland we've been doing really well in signing up to take part with Shetland and South Ayrshire fighting for the top spot. You can keep an eye on how well your area is doing and also sign up on the WWF website.
To take part in Earth Hour all you have to do is put the lights off for the hour between 8.30pm and 9.30pm on Saturday. You could go further by cutting down on even more energy use during this hour, perhaps by not having that cuppa and having some juice instead so you're not boiling the kettle, you could put the TV off and play games and turn the heating down although it is going to be rather chilly in the Northern Isles!
By taking part you'll be showing that you care for the planet and it's future and also help to raise awareness towards the need to take action on climate change. As well as this you may save yourself a few pennies on the next bill!
Iconic buildings all over the world will be taking part and some of our very own Scottish landmarks will be plunging themselves into darkness for an hour. The Wallace Monument, Edinburgh Castle, Holyrood, Eilean Donan Castle, Glasgow City Chambers and Inverness Castle are some of the building taking part in Scotland's Earth Hour.
Dozens of universities, hotels, banks and even supermarkets are set to dim or completely switch off their lights and outdoor illuminated signage for the hour.
The STV studios in Glasgow will also be taking part by switching off some of the lighting on external parts of the building during Saturday evening.
Find out everything that's going on around you for Earth Hour and also see the full list of buildings that are signed up to take part in the world's big switch-off at the WWF website's Scottish pages.
Some of you may decide to keep the lights off all evening but remember before heading off to bed to put the clock forward an hour so that you're ready for the start of British Summertime on Sunday. Remember Sunday is census day too! Enjoy your weekend...
