What are URL parameters?

URL parameters are the extra pieces of data that follow a question mark in a URL, written as key=value pairs and separated by an ampersand. They are used to filter or sort products, pass on searches or track visitors. The page itself usually stays largely the same.

Why are URL parameters important?

Duplicate content: one page can be reachable under dozens of different URLs.
Wasted crawl budget: Googlebot may spend a lot of time on near-identical URLs.
Messy data: split analytics and link value spread across variants.

Examples of URL parameters

?utm_source=newsletter&utm_medium=email
?colour=red&sort=price
?sessionid=8f3a2

How do you deal with URL parameters?

Point to the clean URL with a canonical tag, always link internally to the version without parameters, and keep filter combinations with no search value from being crawled, for example through robots.txt. Check in Google Search Console which parameter URLs Google comes across (technical SEO).

URL parameters