If we used different tabs within the page to show the content, for a example 3 tabs, one for product description, one for specifications and the other for reviews, will the content of these three tabs be taken as three different pages or will it be treated as one page? How will the search engine crawler measure the key word density of the page content?
Not sure exactly what you mean, but the way I am picturing it, I would say it would be three different pages. In that case, the keyword density would be based on only the content within that single tab. On the other hand, if it was all on one page, it would be based on all of the content. Can you explain what you mean by tabs?