Property that you own when you die is typically controlled by the terms of your Will, if you have one. There are numerous exceptions to this rule (such as the use of trusts, beneficiary designations and other planning) that can effectively help someone avoid probate.
A Will, when prepared and signed properly, will direct where your assets go—whether to family members, friends, a charity or somewhere else. However, many people mistakenly believe that having a Will effectively keeps their property and assets out of probate—believing that probate is only for people that had no Will. This is simply untrue. While a Will is effective at authoritatively directing the distribution of assets, such distribution is accomplished directly by the probate process and is subject to the cost and time required. Will or no Will, property would typically go through probate (or a similar court process) unless some additional planning has taken place prior to death. However, there are many estate planning options and tools to effectively avoid probate while accomplishing additional goals, as well. A Will can be an important component of planning—but a Will alone will not keep your assets out of probate.