有的也叫time share，timebank。社区居民互相帮助，利用各自特长，解决家庭所需。不需要钱，但付出的是时间。在各自需要的时候，相互交换。
美国的民间组织，解决很多实际的问题，非常有意思。下面这段视频，是在网上看到的加州long beach的一段介绍。
https://timebanks.org/what-is-timebanking/
Timebanking is a kind of money. Give one hour of service to another, and receive one time credit.
For one person to earn a time credit, however, someone else has to agree to give it. Timebanking happens when a network or circle of members have agreed that they will give and receive credits for services that other members provide. Those networks are called “timebanks.”
