---
title: "What is identity resolution? | Snowplow Signals"
description: "Identity resolution is deciding which events and records belong to the same customer, so their activity forms one profile instead of scattered fragments."
source: https://signals.snowplow.io/learning/customer-profiles-and-identity/what-is-identity-resolution
---

[Learning](https://signals.snowplow.io/learning) / [Customer profiles and identity](https://signals.snowplow.io/learning/customer-profiles-and-identity) 

# What is identity resolution?

Identity resolution is the process of linking the identifiers a customer uses across devices and sessions to a single customer. It turns scattered activity into one profile.

## The problem it solves

One customer shows up under many identifiers: a cookie on their laptop, another on their phone, an email when they log in, an account id after they buy. Left alone, each looks like a different person. Identity resolution is the work of deciding which of these belong together.

## How it is done

Resolution links identifiers using evidence like a shared login, a matching email, or the same device. Some links are certain, like a customer logging in on two devices. Others are inferred from weaker evidence. The next articles cover the graph that stores these links and the two ways of deciding them.

## Why it matters

Until identifiers are resolved, a profile is split across fragments, and a system reading it sees only part of the customer. Resolution is what lets behavior from every device and session add up to one view. It is also optional: activity keyed on a session or a basket needs no resolution at all.

## Put it to work

* [Signals vs a CDP →](https://signals.snowplow.io/evaluate/cdps)

## See it on your own traffic 

Add the SDK, define one attribute, and see an attribute updating against your own traffic in the first session. The free tier runs on the real engine: no card, no sales call.

[Start free](https://signals.snowplow.io/start) [Talk to an engineer](https://signals.snowplow.io/start?intent=engineer) 

More explainers in the [Learning Center →](https://signals.snowplow.io/learning)