User Identity
User identity in analytics refers to a unique identifier - such as an email address, user ID, or account number - that links a specific real person to their tracked behaviors and interactions across sessions and devices.
Also known as: user ID, customer identity, known user
Why It Matters
User identity transforms analytics from aggregate statistics into individual stories. Without identity, you know that someone viewed your pricing page five times - but not whether it was five different people or one person doing deep research. With identity, you can connect the dots across the entire customer journey from first anonymous visit to purchase and beyond.
Identity-based analytics enables you to calculate true metrics like customer lifetime value, actual conversion rates per person (not per session), and real retention numbers. It also unlocks personalization - once you know who someone is, you can tailor their experience based on their history, preferences, and stage in the customer journey.
The shift toward identity-based analytics has accelerated as cookie-based tracking becomes less reliable. First-party identity data that customers willingly provide is more accurate, more durable, and more privacy-compliant than anonymous tracking methods.
Industry Applications
A retailer identifies 35% of their website visitors through loyalty program login, email clicks, and checkout data, allowing them to build detailed purchase histories and personalize recommendations.
A SaaS product uses user identity to track the complete journey from first website visit through trial, activation, and subscription renewal - attributing revenue to the original acquisition source with confidence.
How to Track in KISSmetrics
KISSmetrics was built around person-level identity from the start. Use the identify method to associate a visitor with their email or user ID when they log in, sign up, or submit a form. KISSmetrics automatically merges their prior anonymous activity with their known identity, creating a complete timeline of their journey.
Common Mistakes
- -Using non-persistent identifiers like session IDs instead of stable identifiers like email addresses or user IDs.
- -Identifying users with personally identifiable information in platforms that are not designed to handle PII securely.
- -Not implementing identity at the earliest possible moment, leaving large portions of the user journey anonymous.
- -Creating duplicate identities when the same person uses different email addresses.
Pro Tips
- +Identify users at every opportunity: login, signup, email click, form submission, and support ticket creation.
- +Use a canonical identifier (like an internal user ID) rather than email to avoid issues when users change their email address.
- +Implement identity on both client and server side to ensure you capture identity regardless of how the user interacts.
- +Create an identity resolution strategy that defines how you handle merging when the same person is identified through multiple channels.
Related Terms
Identity Resolution
Identity resolution is the process of connecting multiple identifiers and data points across devices, channels, and sessions to create a single, unified profile for each individual user.
Cross-Device Tracking
Cross-device tracking is the ability to follow and connect a single user's activity across multiple devices - such as smartphone, tablet, and desktop - into one unified behavioral profile.
First-Party Data
First-party data is information collected directly by a company from its own customers and website visitors through owned channels, including behavioral data, purchase history, and voluntarily provided personal information.
Unique Visitors
Unique visitors is a count of distinct individuals who visit a website during a specified time period, where each person is counted only once regardless of how many times they return.
Cookie
A cookie is a small text file stored by a web browser on a user's device that allows websites to remember information between page loads and across visits, widely used in analytics to identify returning visitors.
See User Identity in action
KISSmetrics tracks every user across sessions and devices so you can measure what matters. Start free - no credit card required.