Windows 10 has attained RTM (release to market) status. This means it is at its end of product development and beginning its distribution. WIndows 10 RTM (build 10240) is the version that will be sent to PC OEM partners (to pre-install on new notebooks and desktops), physical media manufacturers, and to the team handling “Get Windows 10”, which is the tool that upgrades eligible Windows 7 and Windows 8.1 installations to Windows 10.
Microsoft will officially launch Windows 10 on July 29th 2015.
Source: TechPowerUp! | News Archive