Glossary

Critical Path

The critical path is the longest sequence of dependent tasks that determines the shortest possible time to finish a project. A delay to any task on the critical path delays the whole project; tasks off it have slack. Knowing yours tells you where a slip actually costs you time.

The critical path is the longest chain of dependent tasks through a project — the sequence that determines the minimum time the whole thing can take. If a task on the critical path slips by a day, the project's end date slips by a day. Tasks that are not on the critical path have some slack: they can move a little without affecting the finish.

The critical path method (CPM) is not ours; it was developed in the late 1950s by James E. Kelley Jr. and Morgan R. Walker and is now a standard scheduling technique documented in the Project Management Institute's A Guide to the Project Management Body of Knowledge (PMBOK Guide), which defines it as the method used to estimate the minimum project duration and the scheduling flexibility on each path.

Why it matters

Knowing your critical path tells you where attention actually buys you time. A delay on a non-critical task can feel alarming but cost nothing; a quiet slip on a critical-path task moves the whole project even if nobody notices. Managing the critical path is how you stop spending energy on the wrong delays.

In practice

You don't need heavy software to think in critical-path terms. Ask: which tasks, if late, push the end date? Those deserve the tightest control points — a clear owner, a dated next step, and an early warning if they wobble — because they are where drift is most expensive.

Frequently asked

Who invented the critical path method?

The critical path method (CPM) was developed in 1956–1959 by James E. Kelley Jr. of Remington Rand and Morgan R. Walker of DuPont, who published the first paper on critical-path planning and scheduling in 1959. It is now a standard technique within the Project Management Institute's project schedule management body of knowledge.

What is the difference between the critical path and float?

The critical path is the longest chain of dependent tasks, and it has zero float — no task on it can slip without delaying the project. Float (or slack) is the spare time a non-critical task has before it would start to push the end date. Tasks off the critical path have float; tasks on it do not.

Can a project have more than one critical path?

Yes. When two or more chains of dependent tasks share the same longest duration, a project has multiple critical paths, and a slip on any of them delays the finish. More critical paths means more places where a single delay costs you time, so each needs the same tight control.

Term

RAID Log

A RAID log is a simple project-management tool that tracks four things in one place: Risks (what might go wrong), Assumptions (what you're taking as true), Issues (what has already gone wrong), and Dependencies (what you're relying on others for). It keeps the sources of drift visible and owned.

Term

Definition of Done

A definition of done is an agreed, shared checklist of the criteria a piece of work must meet before it counts as finished — not just "code written" but tested, reviewed, documented and shippable. It removes the ambiguity that lets half-finished work get called "done".

Guide

What Does It Mean for Work to Be 'Under Control'?

Work is under control when uncertainty has been converted into a usable control point: a clear owner, a dated next step, a decision or escalation date, and a fallback. Control is about predictability, not busyness — a controlled piece of work can still go wrong, but it can no longer surprise you.

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