A team is defined as a group of people responsible for delivering a product. This team can work autonomously, making its own decisions about tools and processes. However, this situation is very rare—it tends to occur only in small organizations. The typical organization has a much more complex, connected IT landscape.
In a modern, agile development organization, there is normally more than one team involved in developing and testing applications. Having multiple teams allows an organization to build more complex products to meet ever-changing customer needs. When multiple teams are involved, responsibilities overlap and dependencies form.
Business processes run across many different teams that must work together to deliver valuable features and working functionality. Dedicated roles at the Team level ensure that all your teams are speaking the same language and not working at cross-purposes.