Flowchart guide

Flowcharts are the most used and most misused diagram type. The grammar is simple; the discipline is in what you leave out.

Start with the happy path

Draw the case where everything works, end to end, before adding a single exception. It is tempting to capture the edge cases as they occur to you, and it produces a chart where the main flow is hard to find.

Decisions carry the policy

A decision shape is where your rules live. "Within 30 days?" is a policy statement, and putting it on the diagram makes it reviewable by whoever owns that policy — which is often not whoever handles the requests.

Loops are information

A connector running backwards means rework. It is usually the most interesting line on the chart, because rework loops are where time disappears. Do not smooth them away.