It starts with a spark, but some ideas catch fire and in the process change the world. Necessity is the mother of invention — from darkness, man found light (the candle) and from even the farthest distances we can still find each other (the telephone). But some inventions have transformed our lives far beyond our homes (the steam engine), our planet (the telescope), and our wildest dreams (the Internet). This countdown highlights how human ingenuity comes in all shapes and sizes. Some were born from the humblest means (the hammer) while others push the limits of what was ever believed possible (the airplane). But regardless of the ratio of inspiration to perspiration, each invention to make the cut was destined to change our lives forever.