Scrum is a type of agile approach that is used in development of software applications. It is just a framework and not a methodology or a full process. It does not provide detailed instructions to what needs to be done rather most of it is dependent on the team that is developing the software, since they know how the problem can be solved. That is why cross-functional and self-organizing teams are essential in case of scrum. There is no team leader in this case who will assign tasks to the team members rather the whole team addresses the issues or problems - everyone is involved in the project right from the idea to the implementation of the project.
As it is an agile methodology, it also makes use of series of iterations or sprints. Some of the features are developed as a part of the sprint and at the end of each sprint; the features are completed right from coding, testing and their integration into the product. A demonstration of the functionality is provided to the owner at the end of each sprint, to obtain helpful feedback for the next sprint.
In a scrum project the focus is on the product. At the end of each sprint, the system or product is brought to a shippable state by the team members.