A consent, in digital marketing, means the agreement of a data subject for the storage and processing of their personal data. Personal data is any information relating to an identified or identifiable natural person. Various bits of information that, if merged, could lead to identifying a particular person, constitute personal data.
Under the EU Data Protection Regulation (GDPR) organizations must obtain consent to collect and process such information.
A Practical Guide to Acquiring Consent in the Age of GDPR
More about consent on the Piwik PRO blog: