They're are the big four of the tech world. They rule our world. But ever wondered how all of these companies have evolved over the past few years? In fact they're extending their borders to unknown territories -- sometimes succeeding in it, sometimes failing. Microsoft started with a simple OS, Apple started with computer hardware, Yahoo started with email application, and Google started with search engine; but in recent years there has been a shift in these companies' strategies, making them swim in unknown waters. NYT has published a "Big-Picture" look at all these companies, making it an interesting read.

"The chart above illustrates many of the services these companies provide. Some of their products have been cornerstone revenue streams, and others are just at the beginning of development. But putting them up against each other really helps illustrate each company’s focus and their possible future directions of exploration."

[via NYT]