Roles are used in different areas:
Accessibility to records users do not own;
Reports: Roles appear as links at the top of Opportunity and Forecast reports, allowing users to access data at different levels of the role hierarchy;
Forecasts: The forecast hierarchy, which determines how forecasts roll up within the company, is automatically generated based on your company’s role hierarchy;
Folders: Access to reports, dashboards, documents, and e-mail templates folders can only be granted via roles;
Knowledge: Access to articles and frequently asked questions from data categories can be controlled via roles.
NB: When deciding to implement the role hierarchy, it is important to understand its scope.
Roles are also used in the definition of automations (workflow, assignment, approval process …).