I had not seen this site till very recently What is a Microsoft account? and it does a great job in explaining what a Microsoft Account is
“It starts with an email address and a password that are used to sign in to services such as Outlook.com, Skype, SkyDrive and Xbox Live, as well as devices such as Windows 8 PCs, tablets and phones, and Xbox entertainment systems. If you use an email address and password to sign in to these or other Microsoft services, you already have a Microsoft account.”
The site covers:
- What is a Microsoft Account?
- Why sign in with a Microsoft Account?
- Security & Privacy.
- Tracking your purchase history.
- How to create a Microsoft Account.
Thanks to Yuki for the tip