A linearized PDF is a PDF arranged so a compatible viewer can display a page before the whole file finishes downloading. It puts the information needed to start viewing near the beginning and includes hints for finding other page data. The same feature is often called Fast Web View.
This can help when you publish a long report, manual or catalogue on a website. A reader may be able to start reading while the remaining data loads. The benefit depends on the viewer and on how the website serves the PDF. Opening a copy that is already downloaded does not test progressive loading. The PDF Association's PDF basics reference lists Fast Web View as linearization.
Choose the operation that matches the job. For a smaller email attachment or an upload limit, use Compress PDF. For progressive viewing from a web link, use Fast Web View. Linearization alone does not lower picture resolution or turn text into images, and its extra structure can increase file size. If you need both operations, finish compression and other edits first, then prepare the final copy for Fast Web View.
Questions
Is a linearized PDF a different file format?
It is still a PDF with the usual .pdf extension. Linearization describes how its contents are stored inside the file. A reader does not need a separate document format, although it needs support for progressive loading to benefit from the arrangement.
How should I check a PDF prepared for a website?
First check that the tool reports successful Fast Web View verification and preview the output for missing or changed content. Then open the hosted PDF through the same kind of link your readers will use. A cached copy may already be downloaded, so it cannot show how a first visit behaves. Verification confirms the file structure; it does not promise a particular loading time.
Why can a verified linearized PDF still wait before showing a page?
The viewer may download the entire file before displaying it, or the server may not deliver the requested portions of the file. Connection speed and the amount of content needed for the first page also matter. If the file opens correctly but starts slowly, check delivery and viewer support before repeatedly rewriting it.
Should I apply Fast Web View before signing or editing a PDF?
Finish edits and prepare Fast Web View before distributing the final document. Later changes can disturb the arrangement, so check it again after saving. Rewriting an already digitally signed PDF invalidates its cryptographic signature. Keep the signed original and do not replace it with a rewritten copy when signature validity matters.