Web
Matrix parameters are alternative to Query parameters. Both can insert optional parameters in a URL.
http://www.example.com/example-page;field1=value1;field2=value2;field3=value3
http://www.example.com/example-page?field1=value1&field2=value2&field3=value3
Matrix Parameter is still in proposal state and is not a Web standard.
Other than format difference, Matrix parameter is more flexible, most importantly it can accept parameter anywhere in the path and not limited to the end:
http://www.example.com/example-page;field1=value1;field2=value2;field3=value3/other-example-page
