For example your web page has 10,000 words content. If anyone sees that webpage, most of the people leave without seeing the web page. So that most of the people leave such web site. So that some webmasters designing a website as divide that webpage 10 pages and ensure 1,000 words per page, last side using Next or previous buttons.
If design a website like that google consider 10 pages are with different content. So If the webmaster use the Canonical URL Tag , the SEO spider considers as all these 10 pages are related to the first (ensured web page) page and give SEO rank for the first page. Consequently the SEO rank may increase.