Windows 10 build 10074

Windows 10 build 10074 is the first officially released Insider Preview build of Windows 10. It was released to Windows Insiders on 29 April 2015.

Cortana

 * Start and Cortana are now more integrated.
 * New experiences in Cortana powered by Bing Instant Answers.

Music and Video Preview Apps

 * Full screen mode has been added to the Music app.
 * You can download movies, TV shows and TV seasons with the Video Preview app on up to three devices.

Other

 * Closing an application in Tablet Mode takes you to the Start screen now.
 * Multi-tasking improvements - Alt+Tab, Task-View, Snap Assist.
 * Windows Store has been expanded to 41 more markets.
 * Windows Store now uses a blue tile instead of gray.
 * New system sounds added, however they were changed to the RTM sounds at a later date.
 * New flat icons have been introduced.