請問pdf是一個甚麼類型的檔案?

PDF
PDF（Portable Document Format的簡稱，意思「攜帶型文件格式」）是Adobe Acrobat輸出得到的一種文件格式。它的優點在於跨平臺、能保留文件原有格式(layout)、開放標準，能免版稅(royalty-free)自由開發PDF相容軟件。

PDF主要由三項技術組成：

衍生自PostScript，可以說是PostScript的縮小版。
字型嵌入系統
資料壓縮及傳輸系統。

PDF編輯器
Adobe Acrobat
Adobe Illustrator（僅可匯入該檔案的某個頁面）
PDF Creator
PrimoPDF
CutePDF

The Portable Document Format (PDF) is the file format created by Adobe Systems, in 1993, for document exchange. PDF is used for representing two-dimensional documents in a device-independent and display resolution-independent fixed-layout document format. Each PDF file encapsulates a complete description of a 2-D document (and, with Acrobat 3-D, embedded 3-D documents) that includes the text, fonts, images, and 2-D vector graphics that compose the document.

PDF is an open standard, and is now being prepared for submission as an ISO standard.

History
When the PDF first came out in the early 1990s, its general adoption was slow.[2] At that time, the PDF-creation tools (Acrobat) and the viewing and printing software had to be bought. Early versions of PDF had no support for external hyperlinks, reducing its usefulness on the world wide web. Additionally, there were competing formats such as Envoy, Common Ground Digital Paper and even Adobe's own PostScript format (.ps); in those early years, the PDF file was mainly popular in Desktop publishing workflow.

Adobe soon started free distribution of the Acrobat Reader (now Adobe Reader) program, and continued supporting the original PDF, eventually, becoming the de facto standard for printable documents.

The PDF file format has changed several times, as new versions of Adobe Acrobat have been released. There have been eight versions of PDF: 1.0 (1993), 1.1 (1994), 1.2 (1996), 1.3 (1999), 1.4 (2001), 1.5 (2003), 1.6 (2005), and 1.7 (2006), corresponding to Acrobat releases 1.0 to 8.0.


Technology
Anyone may create applications that read and write PDF files without having to pay royalties to Adobe Systems; Adobe holds patents to PDF, but licenses them for royalty-free use in developing software complying with its PDF specification.[3]

The PDF combines three technologies:

A sub-set of the PostScript page description programming language, for generating the layout and graphics.
A font-embedding/replacement system to allow fonts to travel with the documents.
A structured storage system to bundle these elements and any associated content into a single file, with data compression where appropriate.

pdf 入面可以有圖 有文字
普通軟件係開唔到
一定要用Adobe果隻reader
或是 你用咩軟件整pdf就用番咩開

Microsoft office中的powerpoint檔....

這種檔最大的特點就是別人不能copy和改

2007-08-03 11:33:56 補充：
絕對不關powerpoint事