red ited ▁by ▁the ▁Media ▁R ating ▁Council ▁on ▁March ▁ 9 , ▁ 2 0 1 0 . ▁Other ▁companies ▁to ▁offer ▁view able ▁impress ions ▁include ▁D MA - Inst itute ▁ ▁On Scroll , ▁C 3 ▁Met rics , ▁Com score , ▁and ▁Ad Y apper , ▁while ▁MS N BC ▁util izes ▁Ser ve View , ▁a ▁propriet ary ▁system ▁in ▁use ▁since ▁ 2 0 1 0 . ▁ ▁The ▁definition ▁of ▁a ▁View able ▁Im pression ▁may ▁depend ▁on ▁the ▁type ▁of ▁the ▁ad ▁units ▁and ▁the ▁reporting ▁system . ▁For ▁example , ▁a ▁View able ▁Im pression ▁for ▁ad s ▁of ▁pre - defined ▁size ▁delivered ▁to ▁ ▁pre - defined ▁space ▁on ▁the ▁content ▁page ▁is ▁registered ▁by ▁Real V u ▁when ▁the ▁Ad ▁Content ▁is ▁loaded , ▁rendered , ▁and ▁at ▁least ▁ 6 0 % ▁of ▁the ▁ad ▁surface ▁area ▁is ▁within ▁the ▁visible ▁area ▁of ▁a ▁vie wer ' s ▁browser ▁window ▁on ▁an ▁in ▁focus ▁web ▁page ▁for ▁at ▁least ▁one ▁second . ▁Click - through ▁is ▁enabled ▁at ▁the ▁moment ▁of ▁the ▁" view able ▁impression ". ▁ ▁View able ▁Im press ions ▁were ▁developed ▁as ▁an ▁improvement ▁of ▁the ▁online ▁impression ▁metrics ▁measured ▁by ▁first ▁ad ▁servers ▁developed ▁in ▁the ▁mid - 1 9 9 0 s , ▁which ▁analyze ▁HTTP ▁requests ▁in ▁a ▁server ▁log ▁and ▁cannot ▁provide ▁information ▁on ▁events ▁fired ▁by ▁a ▁vie wer ’ s ▁browser ; ▁thus , ▁they ▁cannot ▁measure ▁whether ▁ad ▁content