1. In models of communication or persuasion, specific variables associated with the audience (e.g. education) that research has identified as among those that can affect the effectiveness (e.g. the persuasiveness) of a message. In the Yale model these are normally called receiver factors.
2. In market research, all relevant factors relating to the target audience.
3. In audience research (both by academics and media industry researchers), audience variables (e.g. demographic factors) that are identified by researchers and used to analyse patterns of media use and responses to productions.
4. In technical writing, one of the key factors that writers are advised to bear in mind from the outset: for whom are they writing?