File Extensions : What it is used for? Types of File Extensions in Windows 10

A File Extension or filename extension is a suffix at the end of computer file. It comes after the period (dot) and is two, three or four character. File Extension are used by the operating system like Windows to open the particular file.

File Extension also indicates file type or file format. For Example file name is "home.docx". The "docs" file extension is associated with microsoft word or for the documents of your computer.

Importance of File Extension

File Identification:

It allows computer or users to quickly identify the nature of the file content. This provide simple method of keeping all the files of the same type together, making search through lists of files quickly.


It provide the user with a means of verifying the trustworthiness of a file. For example, an EXE file attached to an email from an unknown sender may indicate that the email is malicious. This ".exe" file extension indicates that the attachment is an executable file, rather than a normal attachment. On the other hand, an email with a TXT file, which only contains plain text, attached is not likely to harm the computer.


Windows uses file extensions to determine how it opens different types of files. When a user double-clicks on a file to open it, Windows will open it with the application associated with that file's extension. The Windows system configuration maintains a list of applications and their associated file extensions. These are called "default programs." If a particular file extension is registered with a program, Windows will start that program whenever the user elects to open a file with that extension

Common Types of File Extension in Windows 10

Extension Format

aac, adt, adts Windows audio file

accdb Microsoft Access database file

accde Microsoft Access execute-only file

accdr Microsoft Access runtime database

accdt Microsoft Access database template