Several roles are defined in Scrum; these are divided into two groups; pigs and chickens, based on a joke about a pig and a chicken.^[4]

A pig and a chicken are walking down a road. The chicken looks at the pig and says, "Hey, why don't we open a restaurant?" The pig looks back at the chicken and says, "Good idea, what do you want to call it?" The chicken thinks about it and says, "Why don't we call it 'Ham and Eggs'?" "I don't think so," says the pig, "I'd be committed but you'd only be involved."

So the pigs are committed to building software regularly and frequently, while everyone else is a chicken: interested in the project but really irrelevant because if it fails they're not a pig, that is they weren't the ones that committed to doing it. The needs, desires, ideas and influences of the chicken roles are taken into account, but not in any way letting it affect or distort or get in the way of the actual Scrum project.

[edit] "Pig" roles

Pigs are the ones committed to the project and the Scrum process; they are the ones with "their bacon on the line."

Product Owner

The Product Owner represents the voice of the customer. They ensure that the Scrum Team works with the right things from a business perspective. The Product Owner writes User Stories, prioritizes them, then places them in the Product Backlog.

ScrumMaster (or Facilitator)

Scrum is facilitated by a ScrumMaster, whose primary job is to remove impediments to the ability of the team to deliver the sprint goal. The ScrumMaster is not the leader of the team (as they are self-organizing) but acts as a buffer between the team and any distracting influences. The ScrumMaster ensures that the Scrum process is used as intended. The ScrumMaster is the enforcer of rules and sprints of practice.

Team

The team has the responsibility to deliver the product. A small team of 5-9 people with cross-functional skills to do the actual work (designer, developer etc.).

[edit] "Chicken" roles

Chicken roles are not part of the actual Scrum process, but must be taken into account. An important aspect of an Agile approach is the practice of involving users, business and stakeholders into part of the process. It is important for these people to be engaged and provide feedback into the outputs for review and planning of each sprint.

Users

The software is being built for someone! If software is not used - much like 'the tree falling in a forest' riddle - was it ever written?

Stakeholders (Customers, Vendors)

The people that will enable the project, but are not directly involved in the process.

Managers

People that will set up the environment for the product development organization.