In plain language
Instead of retyping a value, a workflow saves it once, such as a customer ID, and refers to it by name.
Example
A workflow stores the invoice total in a variable, then uses it in both the Slack alert and the accounting entry.
Related terms
Field · Array · Payload · Formatter
Common misconception
A variable’s value is not shared across separate runs unless it is saved to persistent storage; each run usually starts fresh.
Implementation guidance
Name variables clearly, set defaults for missing values, keep secrets out of plain variables, and use persistent storage only when runs must share state.