Why search engines fail to index pages visible on the site

[mech-eng]

Can you explain me why search engines sometimes can not find existing entries. I can find them in the site, I can see them but Google and Bing can not find them.

Best Regards.

 

[jtbell]

Maybe the search engines simply haven't found that content yet. The content might have been added after the search engine spiders last visited the site. Or the site might be structured in such a way as to make the content inaccessible (or at least not easily accessible) to the spiders. For example, it used to be the case that Google couldn't crawl links inside Javascript code; I haven't kept up with this so I don't know if it's still true.

 

[Borek]

What you see and what the search engine sees are sometimes two different things.

Even when the search engine sees something it may choose to not index it. Sometimes per the owner site request - http://en.wikipedia.org/wiki/Robots_exclusion_standard, sometimes because it decides site contains stolen/illegal material.