Google is making a change to its search algorithm to penalize what the company's head of Web spam called "over-optimization" and instead favor websites with high-quality content and less refined search-engine optimization.
Google announced Tuesday that a change in its search algorithm will punish sites that violate the company's "existing quality guidelines" 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 said 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.
However, the announcement included the caveat that not all content punished by the changes will "be easily recognizable as spamming without deep analysis or expertise."
The shift to Google's algorithm is likely to affect, at least initially, some websites that aren't clearly violating its guidelines, according to a strategy paper for Web marketers released earlier this month by the search-engine marketing firm iProspect.
"Based on experiences with Panda and virtually all large algorithm shifts, we do expect sites that don't appear to fit the description of the intended target to nevertheless be caught up in initial sweeps," the iProspect paper said. Panda was a significant change in Google's search algorithm, launched in February 2011, that also aimed to boost the rankings of high-quality sites.
However, "subsequent adjustments and tweaks" will likely restore those users' rankings, iProspect indicated.
Google did not provide specifics about how the algorithm will differentiate useful content from Web spam, saying that doing so would "give people a way to game our search results and worsen the experience for users."
The company says the changes will affect about 3 percent of search queries.
Cameron Scott covers search, web services and privacy for The IDG News Service. Follow Cameron on Twitter at CScott_IDG.