Dependency

Draws what must happen before what, so the one chain that owns your finish date separates from everything with slack.

You have 11 things the article needs before it can go out. You do the easy ones first, then the ones you feel like doing, and three weeks later the piece is still not out, because the whole time you were waiting on one reader you could have asked in week one. The list was honest. It just never said which item was holding the others.

Dependency draws the arrows a list leaves out. Each task or condition becomes a node, and an arrow from one to another means the second cannot start until the first is done. Once the arrows are on the page, two things separate that a list keeps mixed together: the order you happen to work in, and the order necessity requires. Only the second one costs you weeks when you get it wrong.

It has four common renderers. The dependency graph draws nodes and arrows alone, which is enough when you want to find what blocks the most. The critical path adds a duration to each node and traces the longest chain, the chain that sets your finish date. Everything off that chain has slack, meaning it can slip a little without moving the end. PERT keeps each duration as a range rather than one number, so the path length arrives as a spread you can plan against. The prerequisite map runs the same logic over skills and conditions instead of tasks: what has to be true before this becomes learnable.

Use it when many tasks are visible and the blockage is not. The drawing pays off the moment one node turns out to feed four others, because that node is where your next hour goes. It is weak on duration and cost. Arrows carry necessity, not price, so a cheap step and a ruinous one look the same here. And it invites one specific error: drawing the order you are used to instead of the order that is required. On paper, a habit and a prerequisite are the same arrow.