Once you've decided what to share, found your fellow sharers, and decided how you're going to manage your sharing arrangement, you have another decision to make: Do you need a written contract?
Sometimes, you won't really have a choice. Certain agreements will not be enforceable unless they're documented, such as agreements to buy, sell, or otherwise change ownership of land and real estate, or agreements that cannot be completed within a year (such as an agreement to share a camper for the next three summers). These rules differ from state to state and topic to topic, and we'll address them more in later chapters.
But for many sharing arrangements, no law requires a written agreement. As long as the arrangement is fairly simple, your sharing group is small, and you know your sharing partner(s) well and trust them completely, you may reasonably decide not to put the details in writing. For example, if your sister lets you plant a vegetable garden in her back yard, you could sensibly do without a written agreement. You know each other well, there aren't any liability or ownership issues, and it will be easy to discuss any questions that come up.
Generally, however, it's a good idea to put your sharing arrangements in writing. This chapter explains why, explains the documents you might need for various types of arrangements, and discusses how to prepare written agreements that will work for your group and arrangement.