Text should always be presented in digestible chunks. If you’ve written a long article, it is better to split it into several pages.
Sometimes, you would prefer (or be forced) to display the full article in a single browser window. In such cases, you should use intra-document linking so that the visitor is able to jump straight to the required spot.
Another important point: Ensure the long article has sub headings. And make a list of these at the top of the page, just below the main heading. Link these to appropriate spots on the page. Also, provide a ‘Back to top’ link/icon at the end of each sub section.
