Chinese smartphone maker Xiaomi becomes the world's most valuable technology start-up just four years after it was founded.

Data that helped hackers access Sony's internal network came from another group targeting the firm, reports the Washington Post.

United Airlines and travel firm Orbitz have launched legal action against a site that finds cheap airfares.

The majority of visits to sites hidden on the Tor network go to those dealing in images of child sexual abuse, suggests a study.