URL parameters are the parts of a URL after the question mark that carry additional information – the chosen sort order, pagination, a session identifier, or campaign tracking data. The problem arises because every combination of parameters creates a formally different address with almost the same content. The search engine then has to decide which one to treat as the main one, spends crawl budget on them, and signals get split across multiple versions. The solution rests on three steps. Determine the canonical version of the page and link to it from the parameterised variants. Never use campaign tracking parameters in internal links. And do not make unnecessary combinations accessible to crawlers. Likewise, keep a stable order of parameters so that the same combination does not arise in multiple forms.
See also: Faceted navigation, Index bloat, Crawl budget.
