|"Flow Control" refers to the controlling of a respondent's movement through a questionnaire based upon certain rules.
Enabling/Disabling Text and Numeric Questions
One type of basic flow control is the enabling/disabling of text and numeric questions based upon an answer to a previous question. For example, if you had a range-of-values question with the last option as "Other", you would only enable a text question asking for further details if they selected that option, otherwise it would be disabled:
Hiding Irrelevant Pages
The other type of basic flow control is the hiding of one or more pages in a survey based on a respondent's answers. For example, if you had a series of questions about management within a company, you may decide to exclude management from answering the questions themselves. You therefore want to hide a page based on whether the respondent was in management or not: