A linearized PDF (also called a "fast web view" PDF) is structured so that the first page can be displayed before the rest of the file is downloaded. In a standard PDF, all content is loaded before any page is displayed. In a linearized PDF, the file is reorganized so that the first page's data comes first, enabling progressive rendering — viewers see page 1 immediately, with subsequent pages loading as they scroll.
Linearization significantly improves the user experience for long PDFs viewed online. A 50-page report viewed in a browser loads page 1 in seconds even over slow connections, rather than waiting for all 50 pages to download. Linearization doesn't reduce file size — it reorganizes the internal structure. The "Fast Web View: Yes/No" property in Acrobat's Document Properties reveals whether a PDF is linearized.
Creating linearized PDFs: Adobe Acrobat Pro (File → Save As → check "Save as optimized PDF"), Ghostscript (command line: gs -dFastWebView), or various PDF optimization services. When hosting PDFs on websites, linearizing them is a simple optimization that improves perceived load time significantly for long documents.