Answer
When creating a user in Salesforce, you must specify a profile and a role. The profile controls the user's permissions and access to features and data, while the role defines their position in the role hierarchy and level of access to records owned by other users.
Specifying a role is not mandatory when creating a new user in Salesforce. However, it is recommended to assign a role to a user in order to properly manage access to data and records within your organization.