What is GDPR & Data Privacy Compliance?

The Core Problem: Modern data platforms collect millions of events per second: clickstreams, payments, location data, behavioral logs. Without constraints, this personal data is easy to copy, hard to delete, and trivial to misuse. A user's email might exist in production databases, log files, analytics warehouses, machine learning models, cache systems, backup archives, and analyst laptops. When that user requests deletion, how do you find and remove all copies? GDPR treats personal data as toxic material that must be tightly controlled, tracked through its lifecycle, and eventually destroyed. It transforms what was primarily a product and legal problem into a fundamental data engineering challenge. Key Definitions: Personal data means any information that can identify a person directly or indirectly. This includes obvious identifiers like email addresses and phone numbers, but also combinations like IP address plus timestamp plus device identifier that together can uniquely identify someone. Data controller decides why and how personal data is processed (typically product teams), while data processor handles data on behalf of the controller (infrastructure teams, cloud services). Data subject rights give individuals specific powers: the right to access their data, correct inaccuracies, request deletion (right to be forgotten), restrict processing, port data to another service, and object to certain uses. Privacy by design requires embedding privacy protections into system architecture from the start, not bolting them on later. This means data minimization (collect only what you need), isolation of personally identifiable information (PII), pseudonymization (replacing identifiers with tokens), and strict retention limits. From a data engineering perspective, GDPR is primarily about lifecycle control and purpose limitation across distributed systems. Every piece of personal data must have a lawful basis for processing (such as explicit consent or legitimate business interest), and you must be able to prove you handle it correctly throughout its entire lifecycle.