What’s a File Extension?

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A file extension is a suffix at the end of a file name that tells the computer what program is needed to open it. It’s important to know common extensions like .DOC, .TXT, .JPG, and .EXE to recognize files and avoid malicious programs. Changing extensions can cause issues.

A file extension is the suffix at the end of a file name that tells a computer and the computer user what program is needed to open the file. Also called a filename extension, this suffix is ​​preceded by at least one period and is usually one to five characters long, although it is usually three characters long.

Considering that there are thousands upon thousands of software programs available and each has its own extension, it would not be possible to learn them all. However, people will often find themselves remembering the extensions of the most commonly used programs. Many people find it a good idea to familiarize themselves with the most frequently used ones so they can accurately recognize files. Some of the ones that computer users may most often encounter are .DOC, which is usually for Microsoft Word® documents, .TXT for text documents, .JPG for JPEG image files, and .EXE for executable files or files that run a program. When someone comes across an extension they don’t recognize, a quick internet search should be able to reveal the associated software program.

It is useful to make sure a computer shows a file extension name for several reasons. Malicious programs can be sent with executable files with double extensions so that a user does not know what type of file they are really dealing with. Opening a malicious file could expose your computer to a computer virus that could damage your machine and its data.

While it is possible to change the extension of a file, doing so could cause the file to not open properly or even the file to open at all. Some programs are able to read different types of extensions, but others may not know how to recognize the change. For this reason, people should be careful when renaming files. They should make sure to do some research within the program they are using before making any changes to an extension.




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