In the video on this page, “Should I use underscores or hyphens in URLs?  you will see Matt Cutts’ presentation on Google Search Website Optimization. He discusses the use of underscores or hyphens used in website links and how their use is treated by the Google Search feature.

The Google Search web tool is a prominent search engine that rates website search result importance according to PageRank. PageRank is determined by a variety of factors that may include the use of hyphens and underscores in key website locations. This PageRank system is implemented by a series of automated robots also known as spiders, that browse the web and check the properties of every website against a complex set of Google rules.

These rules are proprietary and are kept secret by Google; however they are designed to rank the relevance of websites accurately based on an input search query. That is to say, if we Google the term “classy shoes” we should first see websites that pertain to “dress shoes” and not “sneakers” in search results. Also, particular websites may come across as spam search results when these sites are not properly designed. For these reasons, expert search engine optimization consultation is an invaluable source of information.

Matt Cutts is a Google software engineer and he has the information that people use to optimize their websites for Google Search. He has taken the time to explain what the effect of hyphen and underscore use in website links has on the Google Search engine. You can see this information in the video “Should I use underscores or hyphens in URLs?”