A. PDF (Portable Document Format)
is a cross-platform file format developed by Adobe Systems for delivering
documents electronically in a device- and resolution-independent manner,
with original formatting intact. That is, the PDF version of a document should
look just like the original, but it can be viewed or printed without
access to the application or system used to create it.
Some of the key features of PDF can be
highlighted by comparing it to two common cross-platform delivery mechanisms:
HTML and PostScript.
How PDF differs from HTML:
PDF is a page description language
which expresses the precise image of a document. When rendered on screen or
printed, its layout and appearance matches the author's original.
HTML is a text markup language
which expresses a document's structure and content. The author identifies
key structural elements (headers, paragraphs, tables, text-level elements,
etc.) and the web browser displays its content according to various settings
under the user's control. The layout of the text folows the logical
structure specified by the author, but its appearance is determined by the
browser.
HTML can be parsed by common speech
synthesis software for the blind or visually impaired; it can also be read
through a text-only web browser. PDF is a graphical format, which cannot be
used in either of these ways.
Generally, all of the formatting in an
HTML document must either be coded by hand or with an HTML editor (though
special purpose filters do exist for some programs to output directly to
HTML). PDF files are converted from existing documents, retaining their
original appearance; this allows you to design documents using tools
considerably more flexible than HTML tagging, and still post them on the web
for general viewing.
PDF offers both page-based reading and
browser-style navigation.
While HTML is shown directly in a web
browser, PDF files are shown through a viewer (which has to be installed in
addition to the web browser, either stand-alone or as a browser plug-in).
How PDF differs from PostScript:
Both are page description languages (and
are based on the same imaging model), but PDF can also express some of the
structure of a document.
Unlike PostScript, PDF does not have
control structures and cannot be used as a programming language.
PDF files tend to be considerably smaller
than PS.
PDF has features for interactive viewing
absent from PS:
PDF documents can include hyperlinks
and hypertext objects.
Navigating in a PDF file is fast
(PostScript files are linear, while PDF uses a file structure which
facilitates random access).
PDF files can be byte served over the
web (so you don't have to wait for the whole file to download before you
can start reading it)
PDF contains information such as font
metrics for viewing fidelity, and has features such as font embedding useful
for archiving documents.
PDF files are resolution-independent,
which allows for things like scaling a page to the screen without losing the
clarity of text or graphics (e.g., the magnification features in Acrobat
Reader).
The Acrobat PDF Reader is freely available
for Mac, Windows, and Unix; good PostScript viewers for Mac and Windows are
hard to find.
PDF files can't be downloaded directly to
a PostScript printer (when you print a PDF file from Acrobat Reader, the
program first converts the PDF file to PostScript for downloading).
The above is meant to indicate only some basic
characteristics of PDF; for further details and technical specifications, see
the information on the web about PDF.
A. Acrobat is the Adobe software suite
for creating and viewing PDF files (for complete product information, see
Adobe's Acrobat page).
Flash
Player is installed on 98% of
Internet-enabled desktops worldwide and
on a wide range of popular devices. View
the latest
Flash Player statistics.
What are
the system requirements for Flash Player
8 and Flash Player 9?
Flash
Player 8 and Flash Player 9 support a
broad range of platforms and browsers,
including new browsers such as Firefox
and Safari. View the
system requirements.
Which
browsers and platforms currently
distribute the Flash Player?
To
provide consumers with a virtually
seamless Flash viewing experience, Adobe
distributes Flash Player through many
key partners, including Microsoft,
Apple, Netscape, Novell, TurboLinux, Red
Hat, and AOL. Flash Player is
preinstalled in several web browsers and
on many computers. It is included in
Windows® XP and Apple Macintosh
operating systems.
DirectX is a set of API's (Application
Programming Interfaces) developed by Microsoft that provides direct
access to hardware in the Windows operating system environment. ( An
API acts like a bridge between your program/game and your multimedia
hardware). Each API controls a set of low-level functions that
access the hardware or provide emulation of the hardware if the
hardware does not exist. These functions include support for 2D and
3D graphics acceleration, control over several input devices,
functions for mixing and sampling sound and music output, control
over networking and multiplayer gaming, and control over various
multimedia streaming formats. DirectX through its low level
libraries shifted the burden of hardware support from the developer
to the hardware manufacturer.