1. Keep URLs as short as possible.
Usability impact: According to several studies, people prefer short URLs. Searchers more likely to click a short URL. Google’s Maile Ohye wrote that a long URL “decreases [the] chances of [a] user selecting the listing” in the search engine result pages (SERPs). A Marketing Sherpa study confirms that users click more often on shorter URLs.
SEO impact: Weaker sites with few inbound links are unlikely to see spiders crawling deep content. Spiders may visit and revisit content closer to the root directory more often; these are pages with shorter URLs. Also, it stands to reason that other webmasters and bloggers will be more likely to link to pages with shorter URLs; as a publisher, I trust short URLs more than longer ones and tend to avoid linking to long URLs that I’m not sure will remain active forever.
2. Remove session IDs from URLs.
Crawlability impact: Spiders are less likely to crawl a URL with a session ID because there’s a strong likelihood the content is a copy of another URL. Long parameters can look like session IDS and should also be avoided.
3. Limit variables and parameters in URLs.
Crawlability impact: At conferences, Google’s Matt Cutts has said it’s best to limit the number of parameters in a URL to “2 or 3.” As described in the Google Webmaster Central article referenced above, URLs with too many parameters are likely candidates to be duplicates of other URLs, so spiders try to avoid crawling them.
Usability impact: As mentioned above, users prefer short URLs.
4. Use keywords in URLs.
SEO impact: Keywords in the URL help tell the spider what the page is about. A URL such as www.domain.com/green-widgets.html is obviously about green widgets, whereas a URL such as www.domain.com/product.php?ID=23476234 is not obviously about anything. Keywords in the URL are an additional signal to the spider.
Usability impact: As the Marketing Sherpa study (and many others, too) indicates, users prefer short, clear URLs that help them pre-determine what the page will be about before they click.
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