The Sprint is the central engine of Scrum, where the requirements are converted to features. Maximum duration of the sprint is a month. Based on the need of the project, one can have shorter sprints as well. Sprint durations must be consistent. When you decide on the sprint duration, ensure that all sprints are of the same duration. This will help the teams to be more predictable. All the work necessary to increment the product like the sprint planning meeting, daily scrum, sprint reviews, sprint retrospective and the real development work happen within the sprint.
The sprint starts with the sprint planning meeting. The sprint planning meeting is attended by the scrum master, product owner and the developers. During the sprint planning meeting;
The product owner explains the features to be developed during the sprint.
All the questions regarding the functionality is answered by the product owner or by the specialists invited to the meeting.
The team estimates the weightage (size) of those features independently.
Then the team discusses their estimates and converge into a single estimate for every feature
The team decomposes the features into tasks
Tasks are estimated and rolled up to see whether the size estimates are correct or not. If required, size estimates are fine tuned.
The team checks the effort required and the capacity available and finally commits to a set of features that will be developed during the sprint and finalizes the sprint backlog.
The output of the sprint planning meeting is the agreed upon sprint backlog for the sprint.