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What are file extensions?

File extensions are integral part of any file management system and are very important in computing. Even though file extensions are so important not many people know about them. It happens because operating systems developers are shielding users from file extensions in order to avoid confusion. In this article we will discuss what file extensions are and how they are used in personal computers.

Information in personal computers is stored in files. Each file typically contains information which is formatted in a way which makes it easy for operating system or application to use it. But since multiple applications could be installed on one computer and since operating systems utilize different file formats in order to function properly it is critical for computer to be able to distinguish between different file formats.

That’s why file extensions were introduced. File extensions are suffixes which are added to the end of computer file names. They allow to distinguish between different types of files available on the computer like spreadsheets, documents, executable files, libraries and many more.

Due to the vast number of applications available on the market there are also thousands of different file extensions. When each application is installed it requests to have certain file extensions assigned to it. That is needed for operating system to know which application can open specific file type. If application for a specific file type is not available operating system will report an error opening file and will suggest to look for a suitable application to open it.

File extensions are always appended to the file name with a dot (.) in front and one file can have multiple file extensions assigned to it all delimited by dot (.). Some files may have no file extensions at all which is acceptable. Typically such files are used by the operating system.

By using file extensions computers can quickly look for an application which can open specific file. Instead of looking up through a list of all applications operating system will know exactly which application can open that specific file. This significantly reduces time to open the file.