Most products require someone, or a team of people, who create and build a product. That's where the development team fits into a scrum team. The development team, or dev team, are the professionals who do the actual work of delivering a potentially releasable product or increment.

The done increment, completed by the dev team, is required at the end of each sprint in the sprint review. Kind of, except there is a bit of a difference. In most organizations, the workers are often line managed, and told what to do.

Scrum asks that an organization recognizes that the professionals know what's best to do, and that being given the freedom to self organize makes for A, a better working environment, one where creativity occurs as boundaries are removed. And B, a better product, as the development team having more control of the production will likely be more focused on the quality of the product.

Self organizing teams can seem like managers are giving up control, but scrum asks that the professionals are left to do what they have been hired to do. They'll know how to create the best product.

No one tells the scrum team what to do. They are guided in the processes of scrum by the scrum master, and the product owner is accountable for the product itself. The dev team figures out amongst themselves how to turn backlog items into a product increment.

As mentioned before, it's just the professionals who can create the product increment. This doesn't include the product owner or the scrum master. They sit in a larger scrum team. The development team is cross-functional with all the skills necessary to create the increment.

There aren't any sub-teams, and no one has a particular title on the team, regardless of specialist areas that might need addressing, like product testing or business analysis. There's no team leader or area lead, for example. Individual team members can have specialized skills and areas of focus, but everyone is accountable to the dev team, as a whole.

The dev team needs to be small enough to remain nimble, and large enough to complete significant work within a sprint.

Less than three members of the team decreases the skill base and interaction, leading to smaller productivity gains, meaning they'll likely run in to skill constraints. Having more than nine people requires much more coordination, often creating complexities that can, again, lead to small productivity gains. Aiming to have between five and seven members is often considered the sweet spot for development teams.

Without a dev team, there will be no product. The dev team really is the engine room of a scrum team. Properly nurturing a dev team helps develop the creativity and quality of a product.

The Scrum Team