.pdf and AcroExch.Document

File extension RAR stands for Roshal Archiver. In the same way PK in PKZip stands for Phil Katz. Storing information in a way we see it (words, paragraphs, pages) is very space inefficient. That is why computer scientists invented lots of multiple ways to compress the information. It is actually quite simple to understand who basic principle of compression works. For example if you have document which consists mostly of words "dog" and "cat" you can replace "dog" with "*" and "cat" with "+". Thus "dog chases cat" would look like "* chases +".

.3gp and QuickTime.3gp

File extension DAT stands for DATA. This file extension is used by huge number of applications to store different helpful textual and binary information. Files with DAT extension usually tends to be quite huge.

.torrent and Opera.HTML

If you have problems with any of the format above try finding an application which corresponds to your format.

.pps and PowerPoint.SlideShow.8

Also I'd like to cover one bonus file extension since it became very popular in the age of internet. It is file extension XPI. This extension is used by Mozilla Firefox for installing Firefox extensions over the internet.

.dll and dllfile

File extension BIN stands for BINARY. Binary is a way of representing information in a way which computer could more easily understand. You probably heard that computer doesn't count in a way we do from 1 to 10 but does it in a different way using binary systems where there only 2 digits - 0 and 1. So number 2 will be codes as 10, 7 as 111. So BIN files are usually used to store information coded in binary form which application could use during its work.

Daily quotes

I'm not prejudiced, I hate everyone equally. - Unknown -
The most beautiful thing we can experience is the mysterious. It is the source of all true art and science.
People tend to make rules for others and exceptions for themselves. - Unknown -
Research is what I'm doing when I don't know what I'm doing. - von Braun -
Figures won't lie, but liars will figure. - Gen. C. H. Grosvenor -