Windows 10 (original release)

This article is about the original release of Windows 10 from July 2015. For the overall operating system series, see Windows 10.

Windows 10 (codenamed Threshold; retroactively referred to as version 1507 in documentation) is the successor to Windows 8.1 and the first release of the Windows 10 series, released on 29 July 2015 as a free upgrade for Windows 7 and Windows 8.x users until 29 July 2016 through the Get Windows 10 app. It was intended to address some of the complaints that were made in response to the user interface in Windows 8 and Windows 8.1. It has gained largely positive reviews and has easily exceeded the market share that Windows 8 gained in the same period.

Very early documents refer to this version as Windows 8.2, Windows 9, or Windows TH. According to an unverified rumor, the name "Windows 9" was rejected due to certain apps interpreting an operating system name beginning with that string as belonging to the Windows 9x series. It is more likely that the name change was due to marketing potential. Microsoft explained the skip from number 8 to 10 as reinforcing the importance of Windows 10 as the last major version of Windows, although the company would later break this promise with the release of Windows 11 in 2021.

The Windows Insider Program was introduced with this version, which boosted the company's engagement with its beta testers as well as distributing new releases more frequently than the prior beta testing initiatives. The Insider program was also the first time Windows Update was used to publicly distribute full new builds of the operating system, as opposed to simple patches applied on top of the same build.

Interface
The desktop interface received an update after being unchanged since Windows 7. The Taskbar received a design overhaul with the addition of a search bar, an Action Center button that allows the user to view notifications, and a Task View button that allows users to display all open windows and switch between them and it also allows users to create virtual desktop workspaces.

The DirectUI-based Start screen was removed in favor of a revamped Start menu which is divided into two columns and is based on XAML. The left side of the menu lists links to frequently used applications and user folders. The All Apps button allows the user to view a list of applications installed on the computer. The right side of the menu features titles that can be pinned, resized and rearranged. Some titles are also live meaning that can display information on their titles in real-time. The Start menu can also be resized or be placed into a full-screen UI resembling the Windows 8 Start screen which scrolls vertically instead of horizontally.

The Charms bar was removed completely and replaced by the Action Center, which displays notifications and settings toggles which can be accessed by clicking the Action Center icon in the system tray or swiping from the right side of the screen.

The operating system was redesigned to adapt its UI based on the type of device being used and available input methods. It offers two separate UI modes which include the regular UI optimized for desktops and a Tablet mode designed for touchscreen devices. Users can switch between the two modes and the OS can prompt or automatically switch the UI mode when certain events occur, such as disabling the Tablet UI on a tablet if a keyboard or mouse is plugged in, or when a 2-in-1 PC is switched to its laptop state. In Tablet mode, applications open maximized, and the taskbar is simplified for touchscreen use by adding a back button and hiding the buttons of opened and pinned applications by default, the Task View button is used to switch between applications and the Start menu will also automatically open in full-screen mode.

The search box also incorporates Cortana, an intelligent personal assistant which supports text and voice input. It features functionality such as integration with Bing, setting reminders, a Notebook feature for managing personal information, as well as searching for files, playing music, launching applications and setting reminders or sending emails.

Windows Store apps were overhauled to open in regular desktop windows rather than opening up in full-screen mode in the regular UI. The app commands which were previously available on the Charms bar are now accessed from an app command menu on their title bar.

The login screen was updated to support improved multi-factor authentication technology through Windows Hello which allows users with a supported camera to login with iris or face recognition. The UI design of the login screen and lock screen was also revamped.

The Quick access menu was added to File Explorer to provide quick and easy access to frequently used files and folders. Many system icons were also revamped to follow the Metro design language as well.

The PC Settings app was completely revamped and renamed to simply Settings. It includes more options that were exclusive to the Control Panel such as Windows Update. Starting with this version of Windows, the Control Panel was deprecated as Microsoft started to move settings from the Control Panel to the Settings app.

Windows Update received major changes to its overall functionality and operation. Windows Update no longers allows the manual installation of updates and all updates are now downloaded and installed automatically regardless of type. Users can no longer postpone the mandatory restart for updates as they are only given the option to reboot automatically to install the updates when the system is not being used, or be notified to schedule the reboot. The use of Windows Update is also now mandatory as Windows Update along automatic updates can no longer be turned off within the UI. Cumulative updates were also introduced which packages separate updates into a single update package, mitigating the need for multiple restarts and reducing the number of downloads needed. This means that it is no longer possible to download and install updates that fix individual problems.

Applications
Many changes to the built-in Windows apps can be seen with this release.
 * The Microsoft Edge web browser was introduced to replace Internet Explorer. The latter is still usable and available, although it is now located in the Windows Accessories folder in the Start menu.
 * An updated version of the Windows Store was introduced, featuring a revamped UI that makes it easier to browse and discover apps. It was also updated to feature content from Microsoft's other distribution platforms like Microsoft Movies & TV and Groove Music.
 * The Xbox Video and Xbox Music apps were rebranded as Microsoft Movies & TV and Groove Music respectively. Both apps feature a revamped UI.
 * The classic Calculator app has been removed in favor of the Modern UI version.
 * The Food & Drink, Health & Fitness, and Travel apps have been discontinued.
 * Offline placeholders for files in OneDrive are no longer supported.
 * The Windows Help & Support Center app has been completely removed. Attempting to open it will now direct the user to the Microsoft support website for help content and as a result, it is no longer possible to view help content offline. The WinHelp viewer is also no longer supported meaning that WinHelp files can no longer be opened.
 * Windows Media Center has been discontinued and is removed when upgrading from a previous version of Windows that had the app. Users will receive the paid Windows DVD Player app free of charge upon upgrading.
 * Windows Easy Transfer has been removed.
 * Windows Anytime Upgrade was removed in favor of the Change Product Key utility.
 * Windows Photo Viewer was hidden by default in favor of the Photos app, although it can be brought back using a registry tweak.
 * The Xbox app has received further updates and adds the ability to stream Xbox One games to a Windows 10 PC. The Game Bar was also introduced to provide screenshot and video capture functionality. It also serves as a launcher for all PC games installed on the device.
 * The Action Center Control Panel applet has been renamed to Security and Maintenance.
 * The Backup and Restore Control Panel applet which was previously removed in Windows 8.1, was brought back to provide compatility for backups that were made on the legacy tool.
 * The Windows Console windows can now be resized without restrictions and has many improvements such as the ability to use standard keyboard shortcuts within the console, word wrapping and the ability to move the caret, select and manipulate text. Console windows can also now be made full screen by pressing Alt.
 * The Mail and Calendar apps received updates.
 * Many built-in apps received many updates.

Other changes

 * The UWP platform has been introduced as an extension of the Windows Runtime platform. It provides a core set of APIs common to all variations of the operating system, enabling the ability to code a single application with adaptations (such as UI differences) for different device families including desktops and laptops, tablets, smartphones (via Windows 10 Mobile), Xbox One, and other new device classes such as Surface Hub and HoloLens.
 * DirectX 12 was introduced.
 * The ability to create MS-DOS 8.00 bootdisks has been removed.
 * Drivers for floppy drives are no longer intergrated and must be downloaded separately.
 * Users are now required to manually change the default web browser as the ability for web browsers to automtically set themselves as the user's default browser has been removed to prevent browser hijacking.
 * Parental controls no longer support non-Microsoft browsers or the ability to control browsing using a whitelist.
 * Windows no longer have an accent color on their title bar.
 * The ability to create a guest account was hidden. Although, a guest account can still be created using the Command Prompt.
 * Text on window titlebars are no longer centered.
 * The Security and Maintenance system tray icon is no longer present having been replaced by the Action Center icon.

Windows Update ESD listing
See here for a list of Windows 10 ESD files that have been gathered from the Windows Update infrastructure.

Technical Preview
The Technical Preview was the first phase of the Windows Insider program. The first official build released was 9841, and the last official build released during this phase was build 10061.

Insider Preview
This phase of development began with build 10074, which was a quality build, at least going by the standards set by 10041 and 10049. The final phase of TH1 Insider Preview development ended with build 10166, which was extremely close to the RTM build, build 10240.