What is a Development Team (Developers)?
The development team — current Scrum Guide just says "developers" — is everyone who builds the increment: engineers, testers, designers, writers, whatever skills the product demands. Ideally 10 or fewer, cross-functional, and self-managing: they own the sprint backlog, decide how much work fits a sprint, and organize the how.
The protections around them are structural: the product owner orders the backlog but doesn't assign tasks; the scrum master guards the process but manages nobody. Accountability for the increment is collective — "my part works" is not a sentence the framework recognizes.
Worked example
A seven-person development team — four engineers, a designer, a tester, a data specialist — takes the sprint goal and self-assigns from the board. When the PO tries handing the new API task directly to "her best developer," the scrum master redirects: the team decides who takes what. Two sprints later that task went to the junior instead — slower that week, and now two people can maintain payments instead of one.