Single sign-on

Single sign-on lets a person authenticate once with a central identity provider and reach every connected application without signing in again. In organisations this is typically the corporate directory.

Its security value is centralisation: one place enforces password rules and multi-factor authentication, and — the part that matters most — one place removes access when someone leaves. Without it, offboarding is a checklist of systems that is never quite complete.

It is also the feature that decides whether a product can be sold to a large organisation at all. Above a certain size, an application that cannot join the company's identity system is an application their security review will not approve.