Recently Google has made improvement changes to provide good quality of search results for its users.This chaange will probably impacts 11.8% of its queries.this change is basically to update rankings of low and High quality sites.means some sites witch copies contents from some othe sites or they are not using good quality of sites.in short the sites which are not so use full are called Low quality sites.and the sites which are having information such as research, in-depth reports, thoughtful analysis and so on and also original contents are called High quality sites.

so Google will give high ranking to the high quality sites and decrease the ranking of low quality sites.means some sites will go down and some sites will go up.it is important for healthy web ecosystem.so its a big step of Google in the right direction of helping people find ever higher quality in Google results.for now these change will applied to U.S only but as the time pasts it will apply to all over the world.