Windows 10 is a major release of Microsoft's Windows NT operating system. It is the direct successor to Windows 8.1, which was released nearly two years earlier. It was released to manufacturing on July 15, 2015, and later to retail on July 29, 2015. Windows 10 was made available for download via MSDN and TechNet, as a free upgrade for retail copies of Windows 8 and Windows 8.1 users via the Windows Store, and to Windows 7 users via Windows Update. Windows 10 receives new builds on an ongoing basis, which are available at no additional cost to users, in addition to additional test builds of Windows 10, which are available to Windows Insiders. Devices in enterprise environments can receive these updates at a slower pace, or use long-term support milestones that only receive critical updates, such as security patches, over their ten-year lifespan of extended support. In June 2021, Microsoft announced that support for Windows 10 editions which are not in the Long-Term Servicing Channel (LTSC) will end on October 14, 2025.
In addition to biometric authentication, Windows Hello supports authentication with a PIN. By default, Windows requires a PIN to consist of four digits, but can be configured to permit more complex PINs. However, a PIN is not a simpler password. While passwords are transmitted to domain controllers, PINs are not. They are tied to one device, and if compromised, only one device is affected. Backed by a Trusted Platform Module (TPM) chip, Windows uses PINs to create strong asymmetric key pairs. As such, the authentication token transmitted to the server is harder to crack. In addition, whereas weak passwords may be broken via rainbow tables, TPM causes the much-simpler Windows PINs to be resilient to brute-force attacks.
Windows Update can also use a peer-to-peer system for distributing updates; by default, users' bandwidth is used to distribute previously downloaded updates to other users, in combination with Microsoft servers. Users can instead choose to only use peer-to-peer updates within their local area network.
Windows 10 Home is permanently set to download all updates automatically, including cumulative updates, security patches, and drivers, and users cannot individually select updates to install or not. Microsoft offers a diagnostic tool that can be used to hide updates and prevent them from being reinstalled, but only after they had been already installed, then uninstalled without rebooting the system. Tom Warren of The Verge felt that, given web browsers such as Google Chrome had already adopted such an automatic update system, such a requirement would help to keep all Windows 10 devices secure, and felt that \"if you're used to family members calling you for technical support because they've failed to upgrade to the latest Windows service pack or some malware disabled Windows Update then those days will hopefully be over.\"
In October 2015, Windows 10 began to appear as an \"Optional\" update on the Windows Update interface, but pre-selected for installation on some systems. A Microsoft spokesperson said that this was a mistake, and that the download would no longer be pre-selected by default. However, on October 29, 2015, Microsoft announced that it planned to classify Windows 10 as a \"recommended\" update in the Windows Update interface sometime in 2016, which would cause an automatic download of installation files and a one-time prompt with a choice to install to appear. In December 2015, it was reported that a new advertising dialog had begun to appear, only containing \"Upgrade now\" and \"Upgrade tonight\" buttons, and no obvious method to decline installation besides the close button. 076b4e4f54