There are 4 priority levels on Zendesk. Selecting the correct priority level has a huge impact on how tickets are picked up next to be worked on - and as a result, customer satisfaction can be massively impacted if priorities aren't treated correctly, meaning their ticket is picked up in a timeframe they are unhappy with.
Time-critical tickets that need a resolution immediately. These tickets take huge precedence over all of the other tickets; it should be a 'drop tools and run to rescue' type of scenario. Therefore it's really important to ensure that this priority is only used when expressly required.
For example: WIT has gone offline and no clients or users are able to log in.
Tickets that require attention more quickly than Normal; these tickets usually have a client-facing deadline, or a client is keenly aware of the outcome of this ticket.
For example: a registration order needs to be amended as soon as possible.
These tickets are standard requests, that should be turned around in a reasonable amount of time. A client is normally waiting on the outcome of this ticket, so it needs to be looked at within an acceptable time frame.
For example: a client would like an employment group restructure.
These are tasks that need to be completed but aren't holding up any other processes. They are low-impact and are tasks that can be completed without being under a critical time schedule.
For example: changing font text/colour or layout on the website.
We have a priority matrix over in this post to fully describe the scoring mechanism we use.