Query-String parameters are appended to the URI after a ? with name-value pairs. The name-value pairs sequence is separated by either a semicolon or an ampersand.

For instance, if the URL is http://phonestore.com/api/phones?itemID=itemIDValue, the query parameter name is itemID and value is the itemIDValue. Query parameters are often used when filtering or paging through HTTP GET requests.

Now, consider the online Phone Store API. A customer, when trying to fetch a collection of phones, may wish to add options, such as, android v4.3 OS and 8MP camera. The URI for this resource could look like this: