SAN FRAN­CIS­CO–YouTube says more than one bil­lion peo­ple are now vis­it­ing its on­line video site each month to watch every­thing from clips of cute kit­tens to scenes of so­cial un­rest around the world.The mile­stone an­nounced Wednes­day marks an­oth­er step in YouTube's evo­lu­tion from a quirky start­up launched in 2005 to one of the most in­flu­en­tial forces in to­day's me­dia land­scape.

YouTube crossed the one bil­lion thresh­old five months af­ter Face­book Inc said its on­line so­cial net­work had reached that fig­ure.The vast au­di­ence has giv­en YouTube's own­er, Google Inc., an­oth­er lu­cra­tive chan­nel for sell­ing on­line ads be­yond its dom­i­nant In­ter­net search en­gine.Google bought YouTube for US$1.76 bil­lion in 2006 when the video site had an es­ti­mat­ed 50 mil­lion users world­wide.

Since late 2011, YouTube has re­fo­cused its site to pri­or­i­tize watch­ing along dis­tinct chan­nels of its cre­ators. Such chan­nels were seen as bet­ter al­low­ing ad­ver­tis­ers to fo­cus on cer­tain gen­res of con­tent like beau­ty or mu­sic.