A case team is a team of users working together on a case. A team may include support rep, manager and product manager. Role determines the access level to the cases.
Setup > Customize > Case> Case Teams > Case Team Roles
Case Team Roles > New
Case Team Member Role Page
Member role Name: Test Case Team
Member Role Settings
Case Access: Access to the case records. Access can be “Private or Read Only or Read/Write”.
Visible in Customer Portal: Select if you want the users in this role visible to Customer Portal users viewing cases.
Case team created.