Google Tuesday that a change in its search algorithm will punish sites that violate the company's "existing " and is intended to reward those "making great sites for users, not just algorithms." The change will go live over the next few days, the company said.

Specifically, the changes aim to reduce the amount of content that surfaces high in a user's search results on Google but that is not particularly useful or valuable; this is also known as Web spam.

Matt Cutts, the company's Web spam chief, first mentioned the plan at the SXSW Interactive conference in March.

Cutts the algorithm would assess whether websites "throw too many keywords on the page, or whether they exchange way too many links, or whatever they are doing to sort of go beyond what a normal person would expect in a particular area."

Google has since backed away from Cutts' description of the problem as "over-optimization." The company emphasizes in Tuesday's announcement that the algorithm shift will target only those practices, such as "keyword stuffing" and "link schemes," that violate its guidelines.