Fairshare is a PBS Professional scheduling tool designed to share a cluster’s limited resources according to cluster usage history and allocated percentage. It's the most direct option to grant a percentage of shared resources on the cluster to users, projects, or groups. This white paper covers the creation and management of the fairshare tree structure for your PBS complex. It also covers basic settings and describes concepts of shares within the fairshare tree. Understanding, calculating, and managing entity usage data will not be covered herein. It assumes your familiarity with basic fairshare setup along with the limitations and caveats fairshare has with other PBS Professional scheduling tools. Enabling basic fairshare does not consider fairshare tree capabilities and structure or describe how to create and manage the tree. Granting a percentage of the cluster to individual users may not be viable; the use of your cluster may instead be defined with respect to queues, projects, or accounting. Further, some users may span across multiple groups. Your site’s policy may require the restriction of cluster use to only known entities. PBS Professional’s weighted rooted tree structure provides the opportunity to group entities together and finely manage the balance of resources on your cluster. Adapting resource usage allows you to dictate tracked resources and apply a formula to balance those resources according to your site’s needs.