A standard PDF requires the entire file to be downloaded before rendering starts. A linearized (also called Fast Web View) PDF is restructured so the first page's data comes first, followed by cross-references that let the viewer start rendering after just a few KB. This tool linearizes the input in-browser and drops metadata that isn't needed for web display.
Why linearize?
For PDFs served from a web page (embedded in <iframe>, or opened via a link), linearization means the browser can start displaying page 1 after downloading maybe 5% of the file, then progressively load the rest. Without it, users stare at a blank screen until the whole PDF is transferred.
Metadata cleanup
Alongside linearization, the tool strips: creator/producer strings, XMP metadata, unused resource objects, and file-level XMP. These bloat file size without helping web display. Toggle off if you need the metadata preserved for compliance.
Verification
Open the optimized file in Adobe Acrobat and check File → Properties → Fast Web View: Yes to confirm linearization succeeded. Most modern PDF viewers respect the format transparently.