A file extension is a three character designation that tells software about the format of the data within the file. For example, a ".rtf" file is in rich text format which requires a word processor for it to be interpreted and a ".pdf" file is in portable document format (which requires Adobe Acrobat to interpret).
A file extension is used in some operating systems to identify the type of the contents of the file. It is usually separated from the main part of the file name by a ".", but some operating system have used different characters.
Most file extensions today are 3 characters long (e.g. txt, exe, jpg, mpg), but different operating systems have used file extensions as short as 2 characters to as long as 80 characters.
Some operating systems do not make use of file extensions. For example Unix makes no use of them at all. VMS and the original MacOS used a file type field in the directory entry instead of file extensions.
File extensions are suffixes that show what type of file it is. For example, a basic text file has the extension .txt. Sometimes they're shortened versions of the word, like .txt, but sometimes they stand for something, like .png (Portable Network Graphic). If you want to see file extensions and are on a Windows computer, open up Windows Explorer and select Organize > Folder and Search Options > View > and uncheck "Hide extensions for known file types".
For more info, see here. http://en.wikipedia.org/wiki/Filename_extension
What is the file extension What is the file extension
file extension for video is 101
.html, .php, or .htm
The file extension tells about the type of file, with the extension three letters. For Eg:- *.txt -- text file *.exe-- executable file
file extension
The file extension is ".pages"
the extension of a batch file is ".bat"
The file extension of iPhone firmware file is .ipsw .
The extension .jpeg tells us the file is an image file
The main project file has a VBPROJ extension. This is also a file with the same name as the main project file, but with an SLN extension. The SLN extension is a solution file.
* The file extension of a Word document is .doc * The file extension of an Excel speadsheet is .xls
How to open a PBO file extension?