Chewing gum was incorporated into the earliest versions so
that they could be classified as vending machines. This gave rise to the
fruit symbols on the reels, indicating the flavors of the gum and hence the
name "fruit machine". The symbol of a bell on the reels derives
from the original Liberty Bell machine.
Slot machines spread rapidly across the USA until the
1950s, when federal legislation restricted their use.
Slot machines were originally introduced as an amusement
for the wives and girlfriends of high rolling gamblers, but by the 1990s the
slots had surpassed table games in popularity.
Las Vegas has more that 165,000 slot machines of every
imaginable type. Their success is due to their simplicity, as no skill is
required to play them. New machines are continually being developed - the
latest trend incorporating video and computer technology into dynamic
interactive games.