URL parameters enable information about a specific click or user state to be passed within the URL structure. This segment is also known as a ‘query string’ and resides directly after the question mark (?) at the end of a URL.
A URL parameter is composed of a key and a value, separated by an equal sign (=). If multiple parameters are added to a URL, they are delimited by an ampersand (&). The parameter can be content-modifying, meaning it changes how the content is displayed (e.g., sending users directly to a specific product variation on an e-commerce site).
Alternatively, there are tracking parameters, which contain information about the traffic source, such as an ad campaign or newsletter. This type of parameter does not modify the content display. URL parameters can pose an SEO risk because web crawlers might treat them as sources of duplicate content. Furthermore, these parameters can make URLs less readable and therefore less trustworthy in the eyes of users.