When the Staging version is approved and confirmed as production ready then the staging and production slots can be swapped thus making the Staging version available on the production URL. The end users will still be seeing the production website version (blue) while the Staging (green) version of the site can be tested and re-deployed as many times as needed depending on the testing and development needs and it will not be visible by the production end users. This way different roles within your internal team, like QAs, developers and business stakeholder alike can test the newly released version of your website 'under the hood' without affecting the current stable live website.

The Staging/Live or Blue/Green concept represents the possibility to deploy applications on the same production resources independently and with unique hosting addresses. The concept of Continuous Delivery (CD) and automated deployment process is becoming more and more popular and is an essential step if you want your Sitefinity website to follow best practices. Configure environments using deployment slots

Azure web app deployment slots traffic