Dashes vs. Underscores: SEO Tips

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Difference between Dashes and Underscores

Who would have thought that dashes and underscores would be so important? Of course they obviously do have a value in everyday usage, and you will certainly have to conform to convention when using them in your writing. But there is a deeper significance to the usage of dashes and underscores, particularly for webmasters and anyone else involved in the business of developing and hosting websites. This article aims to show the implications of using each in your website’s URL.



The usage of both underscores and dashes has come about because of the difficulties associated with their use in URLs. The “%20” characters in the browser will always replace a space in the URL, and this can cause a number of issues with regard to readability, as well as the statistics of the page as it pertains to an analytics programs. Both underscores and dashes have a similar effect when used in a web browser.

Usage And Restrictions

Google doesn't consider the underscore a word separator, since the browser itself is the result of the work of programmers. These developers knew that other programmers would frequently search on topics related to programming, wherein using the underscore can significantly change the meaning of a phrase. The usage of the underscore is therefore a concession of sorts to programmers. Also for this reason, using dashes may be a better convention for file names and URLs, although it is not necessarily the best choice for domain names, wherein an underscore may be a better option. Using dashes in domain names may cause your site to be flagged for reasons other than the use of a dash. Dashes are also more appropriate for use in the directory and the file structure.

Google Concerns

Google's crawler reads dashes as separators between words. This is fairly obvious given its behavior with scripted query strings in URLs, particularly with Microsoft's .asp. It seemed that sites that used underscores were less favored by Google, while site URLs that used dashes were regarded more favorably. While the differences may seem to be negligible to some, it may a be a good idea to use dashes instead of underscores in the interest of being more "visible" to Google and the major search engines.



  • Avoids the use of spaces that are translated into the “%20″ characters by the browser
  • Helps prevent readability and statistics issues
  • Too many can cause a site to be flagged
  • Avoided by many web developers
  • More appropriately used in the directory and file structure


  • Avoids the use of spaces that are translated into the “%20″ characters by the browser
  • Helps prevent readability and statistics issues
  • Is not considered a word separator by Google
  • Implemented as a concession to programmers
  • Usage is derived from its use in many computer programming languages 


comments 2 Comments

  • Affordable SEO Services . 3+ yrs. ago

Great work. Dashes are more important for URL's instead of underscores.

Affordable SEO Services Company

  • SEO Services . 3+ yrs. ago

One of the reasons this question is so debated is because of a poorly worded comment made by Google’s Matt Cutts in 2007 that to many people seemed to imply that underscores were treated as word separators.

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