ask ▁or ▁bar rel ▁be er . ▁ ▁In ▁Britain , ▁the ▁Camp aign ▁for ▁Real ▁Ale ▁( C AM RA ) ▁was ▁founded ▁in ▁ 1 9 7 1 ▁to ▁protect ▁traditional — un press ur ised — be er ▁and ▁bre wing ▁methods . ▁The ▁group ▁de vised ▁the ▁term ▁real ▁ale ▁to ▁differenti ate ▁between ▁be er ▁served ▁from ▁the ▁c ask ▁and ▁be er ▁served ▁under ▁pressure . ▁The ▁term ▁real ▁ale ▁has ▁since ▁been ▁expanded ▁to ▁include ▁bott le - condition ed ▁be er . ▁ ▁K eg ▁be er ▁▁ ▁K eg ▁be er ▁is ▁often ▁filtered ▁and / or ▁paste ur ised , ▁both ▁of ▁which ▁are ▁processes ▁that ▁render ▁the ▁ye ast ▁in active . ▁ ▁In ▁bre wing ▁parl ance , ▁a ▁k eg ▁is ▁different ▁from ▁a ▁c ask . ▁A ▁c ask ▁has ▁a ▁tap ▁hole ▁near ▁the ▁edge ▁of ▁the ▁top , ▁and ▁a ▁sp ile ▁hole ▁on ▁the ▁side ▁used ▁for ▁condition ing ▁the ▁un filter ed ▁and ▁un paste ur ised ▁be er . ▁A ▁k eg ▁has ▁a ▁single ▁opening ▁in ▁the ▁centre ▁of ▁the ▁top ▁to ▁which ▁a ▁flow ▁pipe ▁is ▁attached . ▁K eg s ▁are ▁artificial ly ▁press ur ised ▁after ▁fer ment ation ▁with ▁carbon ▁dio x ide ▁or ▁a ▁mixture ▁of ▁carbon ▁dio x ide ▁and ▁nit ro gen ▁gas ▁or ▁especially ▁in ▁Czech ▁Republic ▁sole ly ▁com pressed ▁air . ▁ ▁K eg ▁has ▁become ▁a ▁term ▁of ▁cont empt ▁used ▁by