When you register an application through the Azure portal, an application object and service principal are automatically created in your home directory or tenant.
Reference:
https://docs.microsoft.com/en-us/azure/active-directory/develop/howto-create-service-principal-portal

Reference:
https://support.microsoft.com/en-us/office/obtain-a-digital-certificate-and-create-a-digital-signature-e3d9d813-3305-4164-a820-2e063d86e512
https://docs.microsoft.com/en-us/dynamics365/fin-ops-core/fin-ops/organization-administration/electronic-signature-overview

Reference:
https://docs.microsoft.com/en-us/office365/servicedescriptions/office-365-advanced-threat-protection-service-description

Azure AD Password Protection detects and blocks known weak passwords and their variants, and can also block additional weak terms that are specific to your organization.
With Azure AD Password Protection, default global banned password lists are automatically applied to all users in an Azure AD tenant. To support your own business and security needs, you can define entries in a custom banned password list.
Reference:
https://docs.microsoft.com/en-us/azure/active-directory/authentication/concept-password-ban-bad-on-premises