The "Candidate" slot should be used when you want to test a new configuration version with a small portion of production traffic. Adding a configuration to the "Candidate" slot will allow you to serve a part of your traffic (1%, 5% or more) to this new configuration, and verify that this new configuration doesn’t introduce any errors or issues to your production traffic using our Real Time Monitoring or Log Streaming. Meanwhile the rest of the traffic is served to the configuration occupying the "Current" slot.
Once you have completed your tests and have enough confidence in the new configuration, you can increase the Candidate traffic share by clicking on "Edit Traffic Allocation".
"Traffic percentage" increases are made by you at the pace you desire. Each increase in traffic to the candidate slot causes a corresponding decrease to the current slot. Once the traffic adjustments reach 100%, and the changes candidate configuration is fully vetted, the candidate configuration should be promoted to the "Current" slot causing the candidate slot to be removed until it is needed again. You can do this by clicking on "Edit Traffic Allocation", and then "Promote" the configuration to "Current" slot.