Electricity

As I am exploring the history of civilization and trying to understand the major turning points I noticed things exploded after the introduction of electricity. Once you get a significant portion of the population off of food production duty civilization really takes off.

A lot of the real progress in creating leisure time came after the introduction of electricity.
You had the light bulb to increase the time available for doing things after dark.
You had the electric motor, that alone powers virtually everything that isn't light.
Finally you have the transistor that allows you to make computers and make everything smart.

The lightbulb increases the useful amount of the day you can use and gives you enough light to do useful things. Candles are not really enough to do more then allow you to see others and move from place to place but not read or do detailed work.

The electric motor that runs the clothes washer, the dryer, the dishwasher, the mixer, the blender, the fan, the vacuum, the Walkman, the CD player, the iPod classic, the garage door opener, the Prius, &etc. When the electric motor was first invented people thought they would have one large motor in the basement or somewhere and everything would be run from it by belts, like in the big factories they were retrofitting from the old waterwheel based ones they were replacing. It turns out that lots of little ones in everything is better.

Transistors use electricity too and they let you make things smart. A combination of sensors and transistors allow you to make machines that are pretty smart and very safe and energy efficient. They even let you make light (LEDs) and electricity (solar panels)