http://mdn.i2p/en-US/docs/Glossary/Quality_values
Nevertheless, with the same quality, more specific values have priority over less specific ones: http text/html;q=0.8,text/*;q=0.8,*/*;q=0.8 Value Priority text/html 0.8 (but totally specified) text/* 0.8 (partially specified) */* 0.8 (not specified) Some syntax, like the one of Accept , allow additional specifiers like text/html;level=1 .