Single Sign-On (SSO) Simplified: Understanding How SSO Works in Plain English

(part 1) Discuss how single sign on works and how to implement a SSO server in your software ecosystem in plain English.

Shawn Shi
Geek Culture
Published in
7 min readJan 23


Understand how SSO works based on hotel guest experience. Icon credit to


Do you remember back in the days when you had to remember multiple usernames and passwords for all your online accounts? Accounts for utility bills, phone bills, social media, shopping, online booking for physiotherapist, etc.. Well, I certainly do! I was so tired of trying to manage all those passwords…

What about now? Well, lots of websites and mobile applications support “Sign in with Google”, “Sign in with Facebook” or “Sign in with Twitter”, etc., which has made life a lot easier.

This is the same for enterprises as well. Many companies have implemented a Single Sign-On (SSO) system, which allow their employees to access the company’s resources like websites and apps with just one set of login credentials.

Over the past few years, I’ve got a chance to implement SSO for a few different enterprises’ software systems. Every time when the product was delivered, there was that “aha” moment from them!


Discuss how single sign on (SSO) works and how to implement SSO in an organization at a high-level.

What is Single Sign-On

Single Sign-On (SSO) is a method of authentication that allows users to access multiple applications and systems with one set of login credentials (username and password). The user only needs to enter their login information once, and they will be automatically logged in to all of the systems and applications that they have been granted access to.


Obviously, the two major benefits are:

  1. User convenience as users only need to remember one set of credentials
  2. Improved security by reducing the number of places where user passwords are stored

Before we look at how SSO works for software applications, let’s first recap how a similar concept works for a hotel guest.



Shawn Shi
Geek Culture

Senior Software Engineer at Microsoft. Ex-Machine Learning Engineer. When I am not building applications, I am playing with my kids or outside rock climbing!