Final answer:
File extensions like .txt, .bmp, and .mp3 indicate the type of data in a file and help operating systems determine which software to use to open them. They are not used for encryption but to facilitate the correct handling of the file. Changing file extensions is not recommended as it could make the file unusable.
Step-by-step explanation:
Purpose of File Extensions
File extensions such as .txt, .bmp, and .mp3 serve to identify the format and the type of data contained in a file. They are used by operating systems to associate files with the appropriate software to open them. For example, a .txt file is a plain text file, which can be opened by text editors; a .bmp file is a bitmap image, which can be viewed using an image viewer; and a .mp3 file is an audio file compressed with MP3 compression, which can be played by media players.
The file extension is a critical component of the file name that helps both users and the computer system to understand the nature of the file's contents. The computer uses these extensions to quickly determine how to handle a file when a user attempts to open it. For instance, when a user clicks on an .mp3 file, the system knows to launch an audio player. These extensions do not encrypt the file's contents; rather, their purpose is to provide a clue about the correct program to use to open the file.
It is important to understand that the file extension itself doesn't dictate what is inside a file or its functionality; the true defining feature of a file's purpose comes from the data contained within. However, the extension acts as an important signifier for the correct handling of that data. Users are often advised not to change file extensions as it may render the file unusable or unrecognizable by software applications that previously could open it.