Why is the Will called the Last Will and Testament?

A basic estate plan, which every adult in New York State age 18 years and over needs, consists of a Health Care Proxy and Power of Attorney (both effective only during one's lifetime) and a Last Will and Testament (Will) effective only after someone dies. It is called a "Last Will" because you can make numerous Wills during your lifetime. They may all be valid; however, only 1 is effective - the last one.