Slack, also known as float, is a term used in project management to describe the amount of time available for a task or activity. It is the difference between the earliest and latest possible start or finish times of an activity. Slack can be used to identify potential problems in a project schedule and to determine how much flexibility is available when making changes to the project plan.
The amount of slack available for an activity can be calculated by subtracting its earliest start time from its latest start time, or its earliest finish time from its latest finish time. For example, if an activity has an earliest start time of day 3 and a latest start time of day 5, then it has 2 days of slack. Similarly, if an activity has an earliest finish time of day 10 and a latest finish time of day 12, then it has 2 days of slack.
Slack can be used to identify potential problems in a project schedule. If an activity has no slack, then any delay in that activity will cause delays in other activities that depend on it. This can lead to missed deadlines and cost overruns. Slack can also be used to determine how much flexibility is available when making changes to the project plan. If there is sufficient slack in the schedule, then changes can be made without impacting the overall timeline.