Apple, Facebook, Google, Twitter : What is the greatest common factor

At social-bucket we made a list of inventions of the last decade which have changed the way we live today. And naturally the four names in the title and many more made it to the list. Now that the first part was done, we  tried to figure out what was that one thing that unites all these companies.

that is exactly what all these companies do.

Image courtesy : http://www.theewc.org
And they have built there success stories by connecting people with different flavors.
Google : Connects the data all over the internet and makes it easier to search. Don't forget gmail as connecting tool.
Facebook : Changed the meaning of the "Social" and how we connect with people.
Apple : Showed us the importance of UI in changing our way we communicate and connect with people.
Twitter : Instant sharing and proved that you keep it short and still convey your message.

17th and 18th centuries : It was printing press
19th and first half of 20th century : It was all about Industrialisation
Later 20th century and 21st century : It is all about IT

However even among greatest inventions of all these centuries we can see that the most popular inventions were those which tried to connect people and empowered them to share data. Looks like needs of humanity have always been the same. The last decade has only reiterated this.