what is pii

Your introduction to personally identifiable information: What is PII?

When it comes to personally identifiable information (PII), people are becoming more concerned about data privacy. Identifiable information can be used for illegal purposes like identity theft and fraud. 

So how can you protect yourself as an innocent internet browser? In the case of website owners – how do you protect users and your company from falling prey to privacy breaches?

As one of the most trusted analytics companies, we feel our readers would benefit from being as informed as possible about data privacy issues and PII. Learn what it means, and what you can do to keep yours or others’ information safe.

what is pii

Table of Contents

What does PII stand for?

PII acronym

PII is an acronym for personally identifiable information.

PII definition

Personally identifiable information (PII) is a term used predominantly in the United States.

The appendix of OMB M-10-23 (Guidance for Agency Use of Third-Party Website and Applications) gives this definition for PII:

“The term ‘personally identifiable information’ refers to information which can be used to distinguish or trace an individual's identity, such as their name, social security number, biometric records, etc. alone, or when combined with other personal or identifying information which is linked or linkable to a specific individual, such as date and place of birth, mother’s maiden name, etc.”

What can be considered personally identifiable information (PII)? Some PII examples:

  • Full name/usernames
  • Home address/mailing address
  • Email address
  • Credit card numbers
  • Date of birth
  • Phone numbers
  • Login details
  • Precise locations
  • Account numbers
  • Passwords
  • Security codes (including biometric records)
  • Personal identification numbers
  • Driver license number
  • Get a more comprehensive list here

What’s non-PII?

Anonymous information, or information that can’t be traced back to an individual, can be considered non-PII.

Who is affected by the exploitation of PII?

Most websites you visit collect information about you via tools like Google Analytics and Matomo – sometimes collecting personally identifiable information (PII).

However, anyone can be affected by the exploitation of personal data when websites don’t adhere to the rules. That’s where you have identity theft, account fraud and account takeovers. When websites resort to illegally selling or sharing your data and compromising your privacy, the fear is falling victim to such fraudulent activity. 

PII can also be an issue when employees have access to the database and the data is not encrypted. For example, anyone working in a bank can access your accounts; anyone working at Facebook may be able to read your messages. This shows how privacy breaches can easily happen when employees have access to PII.

Website owner’s responsibility for data privacy (PII and analytics)

To respect your website visitor’s privacy, best practice is to avoid collecting PII whenever possible. If you work in an industry which requires people to disclose personal information (e.g. healthcare, security industries, public sector), then you must ensure this data is collected and handled securely. 

Protecting pii

The US National Institute of Standards and Technology states: “The likelihood of harm caused by a breach involving PII is greatly reduced if an organisation minimises the amount of PII it uses, collects, and stores. For example, an organisation should only request PII in a new form if the PII is absolutely necessary.” 

How you’re held accountable remains up to the privacy laws of the country you’re doing business in. Make sure you are fully aware of the privacy and data protection laws that relate specifically to you.  

To reduce the risk of privacy breaches, try collecting as little PII as you can; purging it as soon as you can; and making sure your IT security is updated and protected against security threats.  

If you’re using data collection tools like web analytics, data may be tracked through features like User ID, custom variables, and custom dimensions. Sometimes they are also harder to identify when they are present, for example, in page URLs, page titles, or referrers URLs. So make sure you’re optimising your web analytics tools’ settings to ensure you’re asking your users for consent and respecting users’ privacy.

If you’re using a GDPR compliant tool like Matomo, learn how you can stop processing such personal data

PII, GDPR and businesses in the US/EU

Because PII is broad, you may run into confusion when considering PII and GDPR (which applies in the EU). The General Data Protection Regulation (GDPR) provides more safeguards for user privacy.

GDPR grants people in the EU more rights concerning their “personal data” (more on PII vs personal data below). In the EU the GDPR restricts the collection and processing of personal data. The repercussions are severe penalties and fines for privacy infringements. Businesses are required to handle this personal data carefully. You can be fined up to 4% of their yearly revenue for data breaches or non-compliance. 

GDPR and personal information

Although there isn’t an overarching data protection law in the US, there are hundreds of laws on both the federal and state levels to protect the personal data of US residents. US Congress has also enacted industry-specific statutes related to data privacy, and the state of California passed the California Consumer Privacy Act. 

To be on the safe side, if you are using analytics, follow matters relating to “personal data” in the GDPR. It’s all-encompassing when it comes to protecting user privacy. GDPR rules still apply whenever an EU citizen visits any non EU site (that processes personal data).

Personally identifiable information (PII) vs personal data

PII and « personal data » aren’t used interchangeably. All personal data can be PII, but not all PII can be defined as personal data.

The definition of « personal data » according to the GDPR:

GDPR personal data definition

This means « personal data » encompasses a greater number of identifiers which include the online sphere. Examples include: IP addresses and URL names. As well as seemingly “innocent” data like height, job position, company etc. 

What’s considered personal data depends on the context. If a piece of information can be combined with others to establish someone’s identity then that can be considered personal data. 

Under GDPR, when processing personal data, you need explicit consent. You need to ensure you’re compliant according to GDPR definitions of “personal data” not just what’s considered “PII”.

How Matomo deals with PII and personal data

Although Matomo Analytics is a web analytics software that tracks user activity on your website, we take privacy and PII very seriously – on both our Cloud and On-Premise offerings. 

If you’re using Matomo and would like to know how you can be fully GDPR compliant and protect user privacy, read more:


We are not lawyers and don’t claim to be. The information provided here is to help give an introduction to issues you may encounter when dealing with PII. We encourage every business and website to take data privacy seriously and discuss these issues with your lawyer if you have any concerns. 

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