The two parts of the tennis court where this shot is generally used are on the baseline and the service line.
Often a player hits a half volley only when forced by the opponent or caught out of position.
The half-volley came to prominence in the hands of George Caridia and Ernest Lewis in the early 1900s.
[1] Arguably the greatest half-volleyer in history is John McEnroe; other professionals such as Stefan Edberg, Pete Sampras and Roger Federer had excellent half volleys that were used as weapons.
Kenny had to learn to hit a half-volley because his serve was so weak that he had to pick up shots at his feet as he came to the net.