Identity Resolution

The PII Encyclopedia

Everything you need to know about personally identifiable information

What is Personally Identifiable Information (PII?)

Personally Identifiable Information (PII) refers to any data that could potentially identify a specific individual. This can include various types of information, such as:

  • Name: Full name, maiden name, mother’s maiden name, or alias.
  • Contact information: Email address, home address, phone number, or social media account identifiers.
  • Identification numbers: Social Security number, passport number, driver’s license number, or tax identification number.
  • Financial information: Bank account number, credit card number, or other financial account information.
  • Biometric data: Fingerprints, retina scans, facial recognition data, or DNA sequences.
  • Health information: Medical records, health insurance information, or other health-related data.
  • Personal characteristics: Age, gender, race, religion, sexual orientation, or marital status.

Essentially, any data that can be used on its own or in combination with other information to identify, contact, or locate an individual is considered personally identifiable information. Protecting PII is crucial for privacy and security reasons, as unauthorized access to such information can lead to identity theft, financial fraud, or other forms of harm.

Why is PII important for advertisers?

As third-party cookies disappear, persistent identity technology, combined with Personally Identifiable Information (PII), will become more crucial. PII is any data that identifies a specific individual. Offline PII data includes Social Security numbers, mailing addresses, and phone numbers. Technology has expanded the scope of PII to include IP and email addresses, login ID’s, social media posts, digital images, geolocation tags, biometric, and behavioral data.

Major browsers are building, or have already built, anonymized means for digital ad attribution via APIs. Building out a robust architecture to interact with each browser’s unique requirements will be a significant undertaking for marketers. Ultimately, all of this still points to a greater need for investment in identity resolution and building a better direct relationship with the customer to take advantage of first-party data and reporting. Marketers must create their own future by building relationships with customers, so they are more willing to share their data and by investing in ways to identify customers across devices.

Data providers, such as Data Axle, are uniquely positioned to help companies onboard their audiences and match them up to search, Facebook, and other data sources. After over 50 years in the business, we are very much a data hub (an axle, if you will) to bring data in and send it out across all marketing channels.

The role of Master Data Management in Identity Resolution

Master Data Management (MDM) is a crucial element in managing Personally Identifiable Information (PII) and plays a significant role in identity resolution. MDM involves creating a unified, accurate, and comprehensive dataset by consolidating information from various sources within an organization. When it comes to PII, MDM ensures that personal data such as names, addresses, and social security numbers are consistently and correctly recorded, reducing the risk of discrepancies and errors. This harmonized dataset is vital for identity resolution, the process of accurately linking and distinguishing individual identities across multiple data systems. Effective MDM supports this process by providing a single source of truth, which enhances data quality and reliability. As a result, organizations can more accurately identify and authenticate individuals, ensure compliance with data protection regulations, and improve the integrity of their data management practices.

How can advertisers keep PII data secure?

Protecting PII is crucial for advertisers to maintain trust with their customers and comply with privacy regulations. Here are some strategies they can employ:


Encrypting PII data both in transit and at rest ensures that even if unauthorized users gain access to the data, they won’t be able to read or use it without the decryption key.

Access controls

Implement strict access controls to limit who can access PII data within the organization. Only individuals with a legitimate need should be granted access, and access should be revoked promptly when it’s no longer necessary.

Anonymization and pseudonymization

Where possible, advertisers can use techniques like anonymization and pseudonymization to reduce the risk associated with handling PII. This involves removing or replacing identifiable information with non-identifying or less identifying data.

Data minimization

Collect and retain only the minimum amount of PII necessary for the intended purpose. This reduces the risk in case of a data breach and also helps to comply with privacy regulations such as GDPR.

Regular audits and monitoring

Regularly audit systems and processes handling PII data to identify and address any vulnerabilities or non-compliance issues. Implement continuous monitoring to detect any unauthorized access or suspicious activities.

Training and awareness

Educate employees about the importance of data security and privacy, as well as their roles and responsibilities in protecting PII. Regular training sessions can help reinforce best practices and ensure compliance with policies.

Secure infrastructure

Use secure infrastructure and follow best practices for securing databases, servers, and other systems where PII is stored or processed. This includes applying security patches promptly, using firewalls, and implementing intrusion detection/prevention systems.

Third-party risk management

If working with third-party vendors or partners who have access to PII, ensure they have robust security measures in place. Perform due diligence assessments to evaluate their security practices and contractual agreements to enforce compliance with data protection standards.

Incident response plan

Have a well-defined incident response plan in place to promptly address and mitigate any data breaches or security incidents involving PII. This plan should include steps for containment, notification, and recovery.

Compliance with regulations

Stay informed about relevant privacy regulations such as GDPR, CCPA, or HIPAA, and ensure compliance with their requirements regarding the handling of PII. This may include obtaining explicit consent for data collection, providing data subjects with access to their information, and honoring data deletion requests. By implementing these measures, advertisers can significantly reduce the risk of unauthorized access or misuse of PII data, thereby safeguarding both their customers’ privacy and their own reputation.

Want to learn more? Check out Audience360 or download a copy of our whitepaper, Connecting the Dots in the Modern Data Landscape.

Lisa Moore
Lisa Moore
Account Director

With over 25 years of data industry experience, Lisa owns a deep knowledge and understanding of actionable data and predictive outcomes. She is passionate about architecting data-driven solutions that fit customer needs and helping them exceed their business goals. She owns avid listening skills, has an insatiable sense of curiosity, and loves to network with like-minded professionals.