Several centuries back, it took more than 75 years for an invention like telephone to reach approxmiately 50,000,000 users. But recently, some start-ups have achieved this milestone in a matter of days. From telephones to automobiles and from airplanes to Facebook, as well as several other tangible and intangible technological products have made a journey into their consumer’s life. Here’s a look at the years they took to make the voyage.