Question - How is security managed in SharePoint?
Answer -
Authentication
SharePoint can run under various IIS modes to authenticate its users. The modes include: Anonymous, Basic, Integrated Windows or Certificates Authentication (over SSL).
Authorization
SharePoint security facilitates the regulation of access privileges of users and groups as well.
Impersonation
.NET Impersonation which is utilized by SharePoint allows an application to run under the context of the client accessing an application.
Deployment and Code Access Security
.NET Code Access Security (CAS) provides a security model. It can restrict the operations that can be performed as well as the resources that can be accessed by managed code.