Scrum poker is used to estimate the relative size of development goals (written as user stories) in Agile Software Development.
In scrum poker, members of a scrum make estimates through the use of numbered cards. The cards are revealed by all members of the scrum team simultaneously to avoid the influence of the other team members.
The cards are revealed and the estimates are discussed. The person with the lowest and the person with the highest values discuss their choices. An optional timer can be used to limit the discussion time.