Microsoft Account (previously Microsoft Wallet, Microsoft Passport, .NET Passport, Microsoft Passport Network, and most recently Windows Live ID) is a single sign-on web service developed and provided by Microsoft that allows users to log in to many websites using one account. The service is commonly referred to as "MSN", because many services incorporating the Microsoft account are or were previously branded with the MSN brand.

Microsoft account allows users to sign in to websites that support this service using a single set of credentials. Users' credentials are not checked by Microsoft account-enabled websites, but by a Microsoft account authentication server. A new user signing into a Microsoft account-enabled website is first redirected to the nearest authentication server, which asks for username and password over an SSL connection. User may select to have his computer remember his login: A newly signed-in user has an encrypted time-limited cookie stored on his computer and receives a triple DES encrypted ID-tag that previously has been agreed upon between the authentication server and the Microsoft account-enabled website. This ID-tag is then sent to the website, upon which the website plants another encrypted HTTP cookie in the user’s computer, also time-limited. As long as these cookies are valid, the user is not required to supply a username and password. If the user actively logs out of their Microsoft account, these cookies will be removed.

Windows Live is the collective brand name for a set of services and software products from Microsoft, part of their software plus services platform. A majority of these services are Web applications, accessible from a browser, but there are also client-side binary applications that require installation. There are three ways in which Windows Live services are offered: Windows Live Essentials applications, web services, and mobile services.

Microsoft said that Windows Live "is a way to extend the Windows user experience".Windows Vista provides a link in its user interface to download Windows Live Messenger, and Windows 7 saw the removal of applications such as Windows Mail, Windows Photo Gallery and Windows Movie Maker and replaced with the Windows Live Essentials suite, a software package that allows the downloading and installation of similar offerings from Windows Live. Microsoft announced that Windows 8 will see Windows Live apps included right out of the box, and will include built-in synchronization technologies powered by SkyDrive.