"Now, share nicely!" - a phrase that every parent of a toddler uses on a daily basis. But how many of us put it into practice ourselves?
And yet sharing our possessions is not only good for other people and the planet, but can also represent a nice little earner.
By renting out everything from your drive to your lawnmower, it's possible to make quite a bit of extra cash. According to research released last week by financial services company ING, the average European sharer made €2,500, last year - and some considerably more.
According to the report, around one in 20 Brits is now making a bit of money on the side by renting out something they own - or is paying to rent something from somebody else. This is about half as many as in the US, and ING says it expects to see 'significant growth' over the next year. Top of the list at the moment is car sharing, although holiday rentals through the likes of AirBnB arew expected to overtake soon.
Those getting involved say it's good for the community, as well as being a way of bringing in extra cash.
"The growth of the sharing economy has been accelerated by new mobile and internet technologies that make it easier and quicker to share," says ING senior economist Ian Bright.
Particularly when it comes to sharing your home, safety is paramount. It pays to use one of the recognised marketplaces, which have contracts and insurance in place.
And, when you do, stick to the system: scammers often suggest bypassing the site through which they originally made contact anddealing direct, potentially leaving you with no protection. And be wary of what you're signing up for: in one case, after signing a 30-day agreement, a US-based AirBnB renter was left with a tenant who refused to leave, citing squatter's rights.
It's also always a good idea to check the ratings and comments left by other users before you make a deal - and do as much research as you can on Google.
So where do you start?
Sharing sites exist for everything from gardening equipment to lifts to work, and new ones are appearing all the time. We look at some of the most popular.
Your spare room
Founded in 2008, AirBnB currently has over a quarter of a million listings in the UK. Owners can list their whole house, or just a room, and set the price and terms themselves. AirBnB collects the payment, releasing it to the owner 24 hours after check-in. It takes a 3% cut on every booking from the host, and between 6 and 12% from guests.
Meanwhile, HomeExchange and LoveHomeSwap deal with holiday swaps - and Vrumi allows you to let out a room in your house as office space. You don't even have sheets to change. StoreNextDoor allows you to rent out your garage, loft or other space for storage.
A ride in your car
BlaBlaCar and Liftshare both allow people to set up city-to-city lift-sharing in the UK. Just let BlaBlaCar know where you're going, and whether it's a one-off trip or a regular commute, and set a price - you should be able to get an idea of the going rate by checking out other listings. BlaBlaCar passengers pay a commission, but the driver gets the full price. With Liftshare, the fee is based on HM Revenue and Customs Approved Mileage Payment Allowance.
Delivering a package
Meanwhile, Nimber allows you to ship goods, rather than people. Simply tell the site where you're going, and it will suggest items that need shipping. You contact the sender and make an offer - and, best of all, the company isn't even taking a cut until more users have signed up.
With car park prices rocketing, many people - especially those with a central location or near an airport - are making good money letting out their drive. JustPark matches drivers with householders - either on a regular basis or as a one-off - taking a 25% commission from the driver.
And just about anything else
With RentMyItems, you can make money out of just about any expensive bit of equipment you own - current listings include jet wases, a PA system, bicycles and a slow cooker. The site doesn't take a commission, but charges listing fees starting at £1 per month per item.
Read more on AOL Money:
Airbnb: How you can make money from your spare bed
How you can earn extra money alongside your job
The best-paid jobs you can do from home