Azure as we all know is a cloud owned by Microsoft. Apart from the cloud services, Active Directory and Disaster recovery support it provides, it also allows a way to brand your own company.
It is basically called company branding. There are different ways you could brand your company. One way is to have your company logo appear while signing in to your Office 365 account.
That is pretty cool and innovative since it makes the employees aware of the brand and Image of the company they are working for. It kind of personalises the whole thing 🙂