Related Research The Data Deprecation Glossary Every Marketer Needs . In this report, Forrester defines frequently used terms in the conversation about data deprecation. Apply Your Data Deprecation Plan . In this report, Forrester explains why data deprecation is happening and how marketers can adapt their marketing approach with transparency, value, and customer relationships in mind. Marketers Face Further Data Deprecation Challenges In Addition To The Death Of The Third-Party Cookie .