glossary — plain english
Lead time & lag time
Adjustments on a dependency between tasks: lead lets the next task start early and overlap, lag forces a wait after the previous one finishes.
Plain finish-to-start is "then." Lead and lag are the fine print. Lead time pulls the second task earlier so the two overlap: "content writing can start during the second half of build" is a finish-to-start link with a week or two of lead. Lag pushes it later: "the concrete needs a week to cure before we build on it" is finish-to-start with a week of lag — nothing is happening, but nothing is allowed to happen either.
You already say both out loud. "While" and "overlap" are lead. "Let it sit," "wait for approval," "give it a week to bake" are lag. The waiting in a lag is real schedule time and belongs on the chart, even though nobody is working — otherwise the plan looks a week shorter than the truth.
A useful habit: when two bars overlap on your chart, be able to say why. Deliberate lead is a planning decision; accidental overlap is usually a missing dependency waiting to surprise you.
See it on a real chart
Describe your project in plain English and ganttchart.ai turns it into a shareable Gantt chart in seconds — every term on this page included. Or read the method first: the plain-English planning guide.