What Is PDF?
According to Wikipedia, PDF (Portable Document Format) is an open standard for document exchange. This file format created by Adobe Systems in 1993 is used for representing documents in a manner independent of application software, hardware, and operating systems. Each PDF file encapsulates a complete description of a fixed-layout flat document, including the text, fonts, graphics, and other information needed to display it.
A PDF file is often a combination of vector graphics, text, and raster graphics. The basic types of content in a PDF are:
- text stored as content streams (i.e., not text)
- vector graphics for illustrations and designs that consist of shapes and lines
- raster graphics for photographs and other types of image
Two PDF files that look similar on a computer screen may be of very different sizes. For example, a high resolution raster image takes more space than a low resolution one. Typically higher resolution is needed for printing documents than for displaying them on screen. Other things that may increase the size of a file is embedding full fonts, especially for Asiatic scripts, and storing text as graphics.
In order to display / read PDF documents on your computer, you need to install appropriate software called PDF reader / PDF viewer. Some of them (mostly free) are: