Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.
When viewing a large PDF file in a network environment, especially when the data rate is low or the network latency high, the user does not want to wait for the whole file to download to view it. This is especially important when the document is being viewed inside a web browser.
We should like the first page to appear quickly, and for changing to another page (by clicking on a hyperlink or a bookmark) to be as fast as possible. In the case of individual pages being large (rather than just the whole document), we should like page content to appear incrementally, most-important content first. Network transport mechanisms such as HTTP (The HyperText Transfer Protocol, used for fetching web pages in a web browser) often allow an arbitrary chunk of data to be fetched. However, because of latency, we wish to fetch a single chunk with all the data for a page, rather than hundreds of little chunks, one for each object.