Historically, once the condemned person was attached to the chair, various cycles (differing in voltage and duration) of alternating current would be passed through the condemned's body, in order to fatally damage the internal organs (including the brain). The first jolt of electric current was designed to cause immediate unconsciousness and brain death; the second one was designed to cause fatal damage to the vital organs. Death was frequently caused by electrical overstimulation of the heart.
The electric chair was invented by Dr Alphonse David Rockwell (1840-1933) and first used in 1890. It was used by more than 25 states throughout the 20th century, acquiring nicknames such as Old Smokey, Old Sparky, Old Betsy, Yellow Mama, and Gruesome Gertie. In the late 20th century, the electric chair was discontinued as a form of execution in many U.S. states, and its use in the 21st century is very infrequent.