URL parameters are put in place to show how search engines should handle sections of your website based on your URLs, in order to crawl your website more efficiently. This refers to folders within a URL string, i.e. example.com/folder-one/ orexample.com/folder-two/, where folder one may have duplicate content to folder two or where the content in folder one should not be showing up in search results.
Websites will usually use canonical tags or robots.txt files to signal to search engines which pages on their website should not be read or indexed in order to avoid duplicate content or prevent unwanted indexing of content.
URL parameters are put in place when websites need to show the same content at different URLs. For example this would occur during a customer’s journey on a shopping site.
Search engines might penalise a website which displays duplicate content without using URL parameters, or another tooltaht designates pages as duplicate content.