Targeting audiences based on their likes and interests related to your product category. For example a luxury bag retailer targeting people who like 'fashion', a hotel aggregation site targeting people who like 'travel' or a drip email software company targeting people interested in 'CRM'. Note that this is a separate tactic from targeting people interested in your product ('black bags', 'rome hotels', 'drip emails') or targeting specific competitors ('gucci bags', 'rome hilton', 'hubspot crm').