I often hear people tell me they need a will so their estate doesn't have to go through probate. They are surprised when I tell them a will is made for probate and guarantees it.
Let me explain: the problem with dying (among other things) is that once you're dead you can't transfer your assets. You can't sign a deed, write a check, make a withdrawal, or otherwise get at your assets. So if you die as the owner of your home, the home is stuck in your name until someone is authorized by a court to act in your place. The same is true for bank accounts, investment accounts, and everything else you own.
Think about it from the perspective of a bank: If someone walks into a bank and tries to withdraw money from an account that isn't theirs, the bank is right to say no. It doesn't matter if the person brings a death certificate and a will and tries to show the bank that the named owner is dead. The bank is not the right party to determine whether the death certificate is real and whether the will is valid. The bank will tell you to go get a court order that authorizes them to hand the money over to someone other than the named owner. That court order is obtained through the Probate Court.
The same is true for your home. What buyer would pay money for a home transferred by someone who isn't the deeded owner? How could the buyer be sure they property really transfers? No lender would lend money for such a transaction, and no title agency would insure it. If you die with your home in your name, your family will have to get a court order from the Probate Court before the home can be sold.
This process of authorizing someone to act in the place of a person who has died is the probate process. A will is an instrument that disposes of property held in your name. A well-written will makes probate easier, but probate is still required.
To avoid probate, you need to transfer property while you're still alive. This is what a trust is for. You form a trust while you're still alive, you place your assets in the trust (you remain in charge of the trust) and you instruct the trust what to do with your assets after you die. When you die, the trust doesn't die. Since the trust owns your home (for example) a person you name in the trust is in charge of distributing the home or its sale proceeds to people you name, just like a will. Only your family doesn't have to go to court.