A query parameter is a key-value pair appended to a URL after a question mark that passes extra information to the page or to analytics, as in ?utm_source=newsletter.
Category
Tracking
Also known as
query string; URL parameter
UTM parameters are the marketing case everyone knows, but query parameters also carry search terms, filters, session tokens, and campaign IDs. They are how a click tells a system where it came from and what it wanted, which makes them central to attribution and tracking.
In practice
Keep marketing query parameters consistent and documented, and be careful what you put in them. Anything in a URL may be logged, shared, and indexed, so never pass personal or sensitive data as a query parameter.
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