Scrum is an iterative, incremental methodology for project
management often seen in agile software development, a type
of engineering. Although Scrum was intended for management
of software development projects, it can be used to run
software maintenance teams, or as a general project/program
Scrum is a process skeleton that contains sets of practices
and predefined roles. The main roles in Scrum are:
1. the “Scrum Master”, who maintains the processes
(typically in lieu of a project manager)
2. the “Product Owner”, who represents the stakeholders and
3. The “Team”, a cross-functional group of about 7 people
who do the actual analysis, design, implementation, testing,
During each “sprint”, typically a two to four week period
(with the length being decided by the team), the team
creates a potentially shippable product increment (for
example, working and tested software). The set of features
that go into a sprint come from the product “backlog”, which
is a prioritized set of high level requirements of work to
be done. Which backlog items go into the sprint is
determined during the sprint planning meeting. During this
meeting, the Product Owner informs the team of the items in
the product backlog that he or she wants completed. The team
then determines how much of this they can commit to complete
during the next sprint. During a sprint, no one is allowed
to change the sprint backlog, which means that the
requirements are frozen for that sprint. Development is time
boxed such that the sprint must end on time; if requirements
are not completed for any reason they are left out and
returned to the product backlog. After a sprint is
completed, the team demonstrates how to use the software.
Scrum enables the creation of self-organizing teams by
encouraging co-location of all team members, and verbal
communication between all team members and disciplines in
A key principle of Scrum is its recognition that during a
project the customers can change their minds about what they
want and need (often called requirements churn), and that
unpredicted challenges cannot be easily addressed in a
traditional predictive or planned manner. As such, Scrum
adopts an empirical approach—accepting that the problem
cannot be fully understood or defined, focusing instead on
maximizing the team’s ability to deliver quickly and respond
to emerging requirements.
Like other agile development methodologies, Scrum can be
implemented through a wide range of tools. Many companies
use universal software tools, such as spreadsheets to build
and maintain artifacts such as the sprint backlog. There are
also open-source and proprietary software packages dedicated
to management of products under the Scrum process. Other
organizations implement Scrum without the use of any
software tools, and maintain their artifacts in hard-copy
forms such as paper, whiteboards, and sticky notes.
The Chicken and the Pig
A number of roles are defined in Scrum. All roles fall into
two distinct groups—pigs and chickens—based on the nature of
their involvement in the development process. These groups
get their names from a joke about a pig and a chicken
opening a restaurant:
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 indifferent
because if it fails they’re not the pigs—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 are not in any way allowed to get in the
way of the actual Scrum project.
The Pigs are the ones committed to the project in the Scrum
process—they are the ones with “their bacon on the line” and
performing the actual work of the project.
Scrum is facilitated by a Scrum Master, also written as
Scrum Master, whose primary job is to remove impediments to
the ability of the team to deliver the sprint
goal/deliverables. The Scrum Master is not the leader of the
team (as the team is self-organizing) but acts as a buffer
between the team and any distracting influences. The Scrum
Master ensures that the Scrum process is used as intended.
The Scrum Master is the enforcer of rules. A key part of the
Scrum Master’s role is to protect the team and keep them
focused on the tasks in hand.
The team has the responsibility to deliver the product. A
team is typically made up of 5–9 people with
cross-functional skills who do the actual work (design,
develop, test, technical communication, etc.).
The Product Owner represents the voice of the customer.
He/she ensures that the Scrum Team works with the “right
things” from a business perspective. The Product Owner
writes customer-centric items (typically user stories),
prioritizes them and then places them in the product
backlog. A Product Owner can be a member of the Scrum Team
but cannot be a Scrum Master.
According to original Scrum, Product Owner is in a "pig"
role. However, in the context of the Sprint and the daily
Stand-Up meetings, the Product Owner is considered a
"chicken" since he has no role in the implementation of
Chicken roles are not part of the actual Scrum process, but
must be taken into account. They are people for whom the
software is being built.
Stakeholders (customers, vendors)
These are the people who enable the project and for whom the
project will produce the agreed-upon benefit[s], which
justify its production. They are only directly involved in
the process during the sprint reviews.
People who will set up the environment for the product
Each day during the sprint, a project status meeting occurs.
This is called a “daily scrum”, or “the daily stand-up”.
This meeting has specific guidelines:
• The meeting starts precisely on time.
• All are welcome, but only “pigs” may speak
• The meeting is time boxed to 15 minutes
• The meeting should happen at the same location and same
time every day
During the meeting, each team member answers three questions:
• What have you done since yesterday?
• What are you planning to do today?
• Do you have any problems preventing you from accomplishing
your goal? (It is the role of the Scrum Master to facilitate
resolution of these impediments. Typically this should occur
outside the context of the Daily Scrum so that it may stay
under 15 minutes.)
Sprint Planning Meeting
At the beginning of the sprint cycle (every 7–30 days), a
“Sprint Planning Meeting” is held.
• Select what work is to be done
• Prepare the Sprint Backlog that details the time it will
take to do that work, with the entire team
• Identify and communicate how much of the work is likely to
be done during the current sprint
• Eight hour time limit
o (1st four hours) Product Owner + Team: dialog for
prioritizing the Product Backlog
o (2nd four hours) Team only: hashing out a plan for the
Sprint, resulting in the Sprint Backlog
At the end of a sprint cycle, two meetings are held: the
“Sprint Review Meeting” and the “Sprint Retrospective”
Sprint Review Meeting
• Review the work that was completed and not completed
• Present the completed work to the stakeholders (a.k.a.
• Incomplete work cannot be demonstrated
• Four hour time limit
• All team members reflect on the past sprint
• Make continuous process improvements
• Two main questions are asked in the sprint retrospective:
What went well during the sprint? What could be improved in
the next sprint?
• Three hour time limit
The product backlog is a high-level list that is maintained
throughout the entire project. It aggregates backlog items:
broad descriptions of all potential features, prioritized as
an absolute ordering by business value. It is therefore the
“What” that will be built, sorted by importance. It is open
and editable by anyone and contains rough estimates of both
business value and development effort. Those estimates help
the Product Owner to gauge the timeline and, to a limited
extent prioritize. For example, if the “add spellcheck” and
“add table support” features have the same business value,
the one with the smallest development effort will probably
have higher priority, because the ROI (Return on Investment)
The Product Backlog, and business value of each listed item
is the property of the product owner. The associated
development effort is however set by the Team.
The sprint backlog is the list of work the team must address
during the next sprint. Features are broken down into tasks,
which, as a best practice, should normally be between four
and sixteen hours of work. With this level of detail the
whole team understands exactly what to do, and potentially,
anyone can pick a task from the list. Tasks on the sprint
backlog are never assigned; rather, tasks are signed up for
by the team members as needed, according to the set priority
and the team member skills. This promotes self-organization
of the team, and developer buy-in.
The sprint backlog is the property of the team, and all
included estimates are provided by the Team. Often an
accompanying task board is used to see and change the state
of the tasks of the current sprint, like “to do”, “in
progress” and “done”.
The sprint burn down chart is a publicly displayed chart
showing remaining work in the sprint backlog. Updated every
day, it gives a simple view of the sprint progress. It also
provides quick visualizations for reference. There are also
other types of burndown, for example the release burndown
chart that shows the amount of work left to complete the
target commitment for a Product Release (normally spanning
through multiple iterations) and the alternative release
burndown chart, which basically does the same, but clearly
shows scope changes to Release Content, by resetting the
It should not be confused with an earned value chart.
Adaptive project management
The following are some general practices of Scrum:
• "Working more hours" does not necessarily mean "producing
• "A happy team makes a tough task look simple"
The following terminology is used in Scrum Roles
The person responsible for maintaining the Product Backlog
by representing the interests of the stakeholders.
The person responsible for the Scrum process, making sure it
is used correctly and maximizing its benefits.
A cross-functional group of people responsible for managing
itself to develop the product.
Product Owner, Scrum Master and Team
Sprint burn down chart
Daily progress for a Sprint over the sprint’s length.
A prioritized list of high level requirements.
A prioritized list of tasks to be completed during the sprint.
Anything that prevents a team member from performing work as
efficiently as possible.
A time period (typically 2–4 weeks) in which development
occurs on a set of backlog items that the Team has committed to.
A report that something is "done". The definition of "done"
may vary from one Scrum Team to another, but must be
consistent within one team.
The Product Owner can cancel a Sprint if necessary. The
Product Owner may do so with input from the team, scrum
master or management. For instance, management may wish to
cancel a sprint if external circumstances negate the value
of the sprint goal. If a sprint is abnormally terminated,
the next step is to conduct a new Sprint planning meeting,
where the reason for the termination is reviewed.
In the Sprint Planning Meeting, the team sits down to
estimate its effort for the stories in the backlog. The
Product Owner needs these estimates, so that he or she is
empowered to effectively prioritize items in the backlog
and, as a result, forecast releases based on the team’s
Relates to an abstract point system, used to discuss the
difficulty of the task, without assigning actual hours.
Common systems of scale are linear (1,2,3,4...), Fibonacci
(1,2,3,5,8...), Powers-of-2 (1,2,4,8...), and Clothes size
(XS, S, M, L, XL).
Definition of Done (DoD)
The exit-criteria to determine whether a product backlog
item is complete. In many cases the DoD requires that all
regression tests should be successful.