what is a file extension and what are the three examples??

Answer 1

They signifiy what type of file it is. Ex: .doc, .xls, .ppt

Great Site:

http://www.filext.com/

Answer 2

A file extension is the dot plus a three letter code after the file name that identifies the type of file it is. For example if you create a file, eg a letter, with Word you need to ensure that it has the extension .doc so the full name would be MyFile.doc. Other examples are xls for Excel files, ppt for Powerpoint files, txt for text only files etc. Another related question is what is the value of extensions? The answer is that its how programs recognise a file it can work on (or one it can't). The file extension is also extremely useful for doing wildcard searches. For example say you created an excel file (with an extension) but don't remember where you put it on the computer. You could search your computer for *.xls and it would list all the excel files on your hard drive. Hope this helps.
Eilish

Answer 3

The file extension is the three characters after the stop. It identifies the file type.

ie

word.doc - a word document

this.xls - an excel spreadsheet

nothing.txt - a text document

Answer 4

Its a sequence of 3 characters after the dot on the end of a filename that indicates the type of file and hence, which program to run in order to view it.

For example :-

.doc = Microsoft Word document
.txt = Plain text, viewable in Notepad or another text editor
.jpg = A graphics file for photos etc., which can be displayed in a graphics program such as Microsoft Paint, Photoshop, etc.

Windows remembers which program to launch by adding information to the windows registry file at the time that programs are installed on your computer.

If you install more than one program capable of viewing the file, windows remembers the last one that was installed.

If you browse through files in Windows Explorer and double-click on a file, the program specified by the registry will be launched in order to view it.

The relationship between file extension and program to view it is known as the 'file association'. Some programs ask at installation time 'Do you want .jpg or whatever to be associated with this program?'.

Here is a link to a site which list the programs associated with each filetype.

Answer 5

A filename extension is an extra set of (usually) alphanumeric characters that is appended to the end of a filename to allow computer users (as well as various pieces of software on the computer system) to quickly determine the type of data stored in the file. It is one of several popular methods for distinguishing between file formats.

With the advent of the GUI, the issue of file management and interface behavior arose. The Windows platform allowed multiple applications to be associated with a given file type, and different file "actions" defined for opening, editing, viewing, and so-forth by means of a context menu. File managers such as Windows Explorer can have applications assigned for almost every file name extension. For example, a text editor for .txt, a word processor for .doc or .odt, a web browser for .htm or .html, PDF viewer or editor for .pdf, a graphics program for .png, .gif or .jpg, a spreadsheet program for .xls or .ods, etc.

Under Microsoft's operating systems DOS and Windows, some extensions, including .exe, .com, .bat, and .cmd, indicate that a file is an executable. This is different from Unix-like operating systems, where file name extensions are voluntary for executables, and instead permissions are used to decide whether a file is executable.

Filename extensions have been in use for decades, but they have gained common usage because the file systems included with DOS and Windows had severe limitations on filenames for many years, which strongly encouraged the use of filename extensions. Filename extensions can be considered as a type of metadata, though one of the most visible pieces of such information on modern computer systems.

Mac OS disposed of filename extensions entirely, instead using a file type code to identify the file format. Additionally, a creator code was specified to determine which application would be launched when the file's icon was double-clicked. Mac OS X, however, uses filename extensions as a consequence of being derived from the Unix-like NEXTSTEP, which didn't have type or creator code support in its file system.

http://en.wikipedia.org/wiki/File_extension

Answer 6

A file extension is the letters after the last period in a file name. This isn't necessarily 3 letters, but that is the most common.

Some examples are: .html - HTML files, .exe - executable files, .sh - shell script files.

Answer 7

File extensions are the 3 letters after the . in a filename,

e.g mySong.mp3 (extension mp3 meaning its an mp3 (music file))
downloadedFile.zip (zip meaning its compressed by a zip program)
runMe.exe (exe is an executable meaning it runs as a program)

Answer 8

hi there,
http://en.wikipedia.org/wiki/Filename_extension
this link will allow you to have full info on the files