Understanding Critical Paths

Critical path: It refers to the sequence of project network activities which add up to the longest overall duration. Identifies the shortest time possible to complete the task.
Float or Slack: The total time that you can delay a task without it delaying the project. More slack means more flexibility.
Critical Activities: These are the activities that have zero flexibility. A delay in any of these activities would imply a delay for the whole project.
Early Start (ES) and Early Finish (EF): The earliest times at which an activity can start and finish, given its precedence relationships.
Late Start (LS) and Late Finish (LF): The latest times by which an activity must start and finish to not delay the project.

The Process of Creating a Critical Path

Activity Identification: Identify all the specific activities and milestones.
Activity Sequencing: Determine the proper sequence of the activities.
Activity Duration Estimating: Estimate the time resources required to complete each activity.
Network Diagram: Show the order of activities.
Critical path Analysis: Determine the longest path through the network diagram and the earliest and latest an activity can start without making the project longer.
Schedule Development: Use the activity sequence, duration, resource requirements and schedule constraints to create the schedule model for project execution and monitoring.