If you're buying property with one or more other people, you must choose how to take title. It's an important decision--there are significant differences between tenancy in common and joint tenancy.
Holding property as "joint tenants" is a way for two or more people to share ownership of real estate. In all but a few states, the joint tenants must own equal interests in the property; for example, if you buy a home with two others, you each own a one-third interest.
When one joint tenant dies, the remaining owners automatically own the deceased owner's interest in the property. For example, if a parent and child own a house as joint tenants and the parent dies, the child automatically becomes full owner. Because of this right of survivorship, a will is not required to transfer the property; the property goes directly to the surviving joint tenants without the delay and costs of probate.
Holding property as "tenants in common" is another way that two or more people can own real estate together. Unlike joint tenants, tenants in common can hold property in unequal shares. And each of you can leave your interest to beneficiaries of your choosing--it won't automatically go to the surviving co-owners. In some states, two unmarried people are presumed to own property as tenants in common unless they've agreed otherwise in writing.
Depending on where the property is, married couples may also take title as "tenants by the entirety" or as "community property" or "community property with right of survivorship." Community property states are Arizona, California, Idaho, Louisiana, Nevada, New Mexico, Texas, Washington, and Wisconsin. (And in Alaska, spouses can sign an agreement making specific assets community property.)
To take property in joint tenancy, tenancy by the entirety, or tenancy in common, you don't need any special kind of deed. You'll just specify, in whatever deed you use, how the new owners are taking title.
For help in filling out a deed to transfer California property, see Deeds for California Real Estate, by Mary Randolph (Nolo).