On average PDF is smaller than HTML. To see this one must take into account all of the files which make up a web page. PDF's small size in relation to HTML is due to PDF's compression of text and graphics. However, whenever an HTML file contains just text and makes no additional requests to the server, PDF is actually larger. This size difference becomes very apparent when dealing with an entire site. A website with a lot of graphics (e.g., two or three imagemaps, GIF bullets everywhere) could take up to 1.5MB, while the PDF could take as little as 290k. When comparing individual pages, a PDF file can be smaller as well. The Vertec home page in HTML is 48k, but in PDF (by downsampling to 72 dpi) the file is 31.6k.As far as speed, on average a PDF page is faster than an HTML page. This statement is based on a few factors:
However, the speed of web pages is not a purelyobjective measurement; it has elements of psychology as well. A carefully written HTML document may make all of its text visible quickly, and then display graphics. Because a reader may be able to use the page more quickly, they may see it as a faster page than a PDF which would actually be finished more quickly
Use the base 13 fonts, do not use ASCII encoding, use Font Subsets, and use the same type of restraint with graphics as you do with HTML
When you use a font in a PDF file, it can be embedded, which increases the file size. Normally, a 'font descriptor' is included. This is smaller than the font and just gives information on the sizes and style of the characters in the font. However, some fonts are 'built in' to the PDF specification, and do not even need a descriptor. It follows that using these fonts may produce the very smallest PDF files. There are actually 14 fonts like this. The term 'base 13' comes from PostScript, and represents the 13 fonts found in almost all PostScript printers. They are Times, Helvetica and Courier (4 variants of each: regular, bold, italic and bold italic), plus the Symbol font. PDF adds ZapfDingbats to this list. In some circumstances common fonts such as Times New Roman and Arial function act as substitutes, but this depends on a number of factors.
The World Wide Web is a collection of documents which are served via the HyperText Transfer Protocol (HTTP). Each type of document is identified by a MIME type which is registered with the IANA. For instance, HTML is identified by text/html and PDF is identified by application/pdf. This is provided that the web server has been set up properly by the site administrator. If your PDF files are being sent as text/plain (the browser shows the file's contents), then you may need to have your site administrator add application/pdf to their mime.types file.
A web browser interacts with the documents sent to it via HTTP. Almost all browsers recognize HTML, plain text, and GIF files and are able to display these files within their window. For other file types, a browser relies on helper applications. Every file a browser receives is saved to disk in one form or another. For HTML, the browser opens and renders the file. For files which use a helper application, the file is saved and then the helper application is asked to "help" with the file. (Helping may not always be visible - for instance a helper for a sound file would play the sound.)
To work with PDF files via the World Wide Web, you need to setup your browser so that it knows to use Acrobat Reader (or another PDF viewing application like Acrobat Exchange). The program will help by displaying the file on the screen. A new Netscape plug-in and Internet Explorer ActiveX control are in development by Adobe. These plug-ins will enable these browsers to display a PDF in their own windows
Other browsers than those listed in the following sections allow for helper apps, and a description of how to set helpers up should be available in their help file. Just remember that PDF's MIME type is application/pdf and everything should set up fine
For Internet Explorer, most versions use the file associations. So for PDF and Windows 95:
**Replace acroread with the name of the executable you are using to view PDFs.
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