There are 4 different lanes in a scrum board which includes To Do, In Progress, Testing, and Ready.
The To Do swim lane holds user stories that have not been started. Once you start implementing one of these user stories it is moved to In Progress.
The In Progress swim lane holds user stories that have been started, but not finished. Once you start implementing one of these user stories it is moved to Testing.
The Testing swim lane holds user stories that have been finished but have yet to be reviewed by anyone on the team. Once it has been reviewed and accepted the user story is moved to Ready.
The Ready swim lane holds user stories that have been finished and reviewed. This is the last phase.
Catalyte Scrum Blog 