A Microsoft account or MSA (previously known as Microsoft Passport, .NET Passport, and Windows Live ID) is a single sign-on personal user account for Microsoft customers to log in to consumer Microsoft services (like Outlook.com), devices running on one of Microsoft's current operating systems (e.g. Microsoft Windows computers and tablets, Xbox consoles), and Microsoft application software (including Visual Studio).
Overview
Microsoft account allows users to sign into websites that support this service using a single set of credentials. Microsoft account offers a user two different methods for creating an account: Use an existing e-mail address: Users are able to use their own valid e-mail address to sign up for a Microsoft account. The service turns the requesting user's e-mail address into a Microsoft account ID. Users may also choose a password of their own choice. Sign up for a Microsoft e-mail address: Users can also sign up for a free e-mail account through Outlook.com or MSN, with Microsoft's webmail services designated domains (i.e. @hotmail.com, @outlook.com, @msn.com) that can be used as a Microsoft account to sign into other Microsoft account-enabled websites. The e-mail domains @live.com and @passport.com are discontinued but maintained.
Microsoft websites, services, and apps such as Bing, MSN and Xbox Live use Microsoft account as a means of identifying users. There are also several other companies that use it, such as the Hoyts website which is hosted by NineMSN.
Windows XP and later has an option to link a local Windows user account with a Microsoft account, thus automatically logging users in to their Microsoft account whenever a service is accessed. Starting with Windows Server 2012, Windows allows users to directly authenticate into their PCs using their Microsoft account rather than a local or domain user.
Login methods
In addition to using an account password, users can login to their Microsoft account by accepting a mobile notification sent to a mobile device with Microsoft Authenticator, a FIDO2 security token or by using Windows Hello. Users can also set up two-factor authentication by getting a time-based, single-use code by text, phone call or using an authenticator app.
Technical details
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. The user may select to have their computer remember their login: a newly signed-in user has an encrypted time-limited cookie stored on their 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.
History
Microsoft Passport, the predecessor to Windows Live ID, was originally positioned as a single sign-on service for all web commerce. Microsoft Passport received much criticism. A prominent critic was Kim Cameron, the author of The Laws of Identity, who questioned Microsoft Passport in its violations of those laws. He then joined Microsoft in 1999 after his company was acquired and was its Chief Architect of Access and Identity until his 2019 retirement, helping to address those violations in the design of the Microsoft Account identity meta-system. As a consequence, Microsoft Accounts are not positioned as the single sign-on service for all web commerce, but as one choice of many among identity systems.
In December 1999, Microsoft neglected to pay their annual $35 "passport.com" domain registration fee to Network Solutions. The oversight made Hotmail, which used the site for authentication, unavailable on December 24. A Linux consultant, Michael Chaney, paid it the next day (Christmas), hoping it would solve this issue with the downed site. The payment resulted in the site being available the next morning. In Autumn 2003, a similar good Samaritan helped Microsoft when they missed payment on the "hotmail.co.uk" address, although no downtime resulted.