Some of these ideas around alternative economics can seem overwhelming, but here's one most people can get their head around. You're at a bar, and someone buys you a beer. Lucky you! You've just entered a gift economy.
The interesting thing about gift economies is implied trust. If someone buys you a beer, there are usually some unspoken strings attached. Either you are expected to reciprocate and buy the person a beer later that night or later in the week. Or there are unspoken expectations that you will repay the gift in other ways like a ride to the airport, helping the giver move into a new apartment, or less tangible things like personal attention or support. The exchange is implicit.
If the exchange isn't completed, meaning in our example you do not buy your friend a beer later that night, or do not return the phone call when your friend asks for a ride to the airport, there are consequences. You may feel guilty, you may gain a reputation as a flake amongst your friends, and worse yet, your friend may never buy you a beer again.
In this way, rather than "getting something for free," gift economies encourage and strengthen trust between those involved.