Vacuum Cleaner

Here's how inventor H. Cecil Booth came up with the idea. He noticed a device on trains that blew dust off chairs and thought it would be better to have a device that sucked the dust instead. To test his idea he laid a handkerchief on a chair, put his mouth on it and sucked as much dust as he could. Seeing the amount of dust and dirt on the underside of the hanky effectively made it the first vacuum cleaner filter and realized the idea could work. It's a good thing he wasn't looking to invent a machine that cleans manure.

Source: http://gilbertm.hubpages.com/hub/inventions20century

LCD (1970)

An LCD or liquid crystal display is a type of flat panel display commonly used in digital devices, for example: digital clocks, appliance displays, and portable computers.

How an LCD Works

According to a PC world article, liquid crystals are liquid chemicals whose molecules can be aligned precisely when subjected to electrical fields, much in the way metal shavings line up in the field of a magnet. When properly aligned, the liquid crystals allow light to pass through.

A simple monochrome LCD display has two sheets of polarizing material with a liquid crystal solution sandwiched between them.

Source: http://www.historylearningsite.co.uk/inventions-and-discoveries-of-the-twentieth-century/inventions-1900-to-1990/

Compact Disc, 1980

Electronics giants Sony and Phillips joined forces to design a digital audio disc as a spin-off from those cumbersome and expensive Laserdiscs. The CD was commercially available in 1982. As costs of development for CD's and CD players became lower it became the primary format for music. Although MP3's are quickly replacing CDs as the primary media for music today, CD technology is still used in CD-ROMs, DVDs, and Blu Ray. I can't imagine physically rewinding or fast forwarding anything anymore
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Source: http://gilbertm.hubpages.com/hub/inventions20century

Rocketry

While the rocket was first invented and used by the Chinese over three thousand years ago—and used occasionally by the Greeks and Romans since —it wasn’t until the twentieth century that it came into its own and became more than just a dazzling amusement or a largely harmless but still effective “terror weapon” for ancient armies. In the twentieth century, rockets became bigger and more powerful. Most importantly, they became controllable, which suddenly made them useful both as weapons of war and, even more vitally, as our means of accessing outer space. Without the rocket, it is safe to say we would not only have never gone to the moon or visited every planet in our solar system. Rockets also place satellites into orbit around our planet, so without them we also wouldn’t be able to use GPS, predict the weather, make international calls or, for the most part, even use our cell phones much of the time.
Source:http://www.toptenz.net/top-10-inventions-of-the-20th-century.php

Radio

Few people today can appreciate the impact the advent of radio had on the twentieth century. Not only did it suddenly make it possible for a person to be heard from hundreds or even thousands of miles away without the use of a wire (quite an accomplishment in the first years of the century) but it was the center of family life through the end of the Second World War and into the doldrums of the fifties, when it was gradually replaced by that new-fangled contraption, the television. Today, it seems to only be useful in the car as a means of keeping the driver from falling asleep behind the wheel or as a tool of talk radio designed to rile the masses. In its day, however, it was every bit as vital to existence as the television, the computer, the microwave, and the cell phone are to us today.

Source:  

http://www.toptenz.net/top-10-inventions-of-the-20th-century.php

The Internet

The computer rendered the typewriter obsolete and made writing in long-hand a thing of the past, but it took the internet to truly turn the computer into the monster it is today. While the airplane shrank our planet to the point that one could fly from New York to London in six hours, the internet made it possible to be there in a few seconds. It allows truth to make it into and out of repressive countries, it foments revolutions, and spreads lies at the speed of light. It also gives anyone the ability to buy and sell almost anything imaginable, find and torment old school mates, watch the latest you-tube videos, and even find their perfect life partner, all for a few bucks a month. Oh, and you can also get useful information off it if you don’t mind scrolling through 15,000 hits to find out just how long snails really live. Where would we be without it?

Source:

http://www.toptenz.net/top-10-inventions-of-the-20th-century.php

Nintendo Wii (2006)

This video game console was launched by Nintendo on November 19, 2006. Its main competitors are Microsoft's Xbox 360 and Sony's PlayStation 3.

However, the Wii has one distinguishing feature from Xbox and PS3 - users can play video games by making use of special wireless controller called the Wii Remote. The latter detects the user's movements in 3D.

In December 2009 the console managed to break the record for best-selling gaming console in one month in the US. As of May 2011, Nintendo's device is the leading console in sales around the world, followed by PlayStation 3 and Xbox 360.

source: http://www.infoniac.com/hi-tech/top-10-most-important-inventions-of-the-21st-century-in-technology.html