Common File Extensions and Formats (प्रमुख फ़ाइल एक्सटेंशन)

In computer operating systems, a File Extension is a suffix of 3 or 4 characters appended to the end of a filename following a dot (.).

It serves as an identification badge that tells the Operating System:

1. 1
   What type of data is stored inside the file (Text, Audio, Video, Image, Program).
2. 2
   Which default application program should be launched to view and edit it.

In the NIELIT CCC exam, questions testing default extensions of LibreOffice, MS Office, audio, video, and compressed files appear in almost every examination paper!

1. Office Productivity Extensions (CCC Exam Super Important)

Pay special attention to the difference between LibreOffice (OpenDocument) and Microsoft Office:

2. Text & Document File Extensions

• .txt (Plain Text): Raw unformatted text created by Notepad. Consumes minimal storage.
• .rtf (Rich Text Format): Text format supporting basic font styling, colors, and bold text created by WordPad.
• .pdf (Portable Document Format): Developed by Adobe. Universal read-only document format that looks identical on any device, phone, or operating system without altering layout or fonts.

3. Image File Extensions (तस्वीरें)

• .jpg / .jpeg (Joint Photographic Experts Group): The standard compressed image format used by digital cameras, smartphones, and web pages. Uses lossy compression.
• .png (Portable Network Graphics): Supports transparent backgrounds (पारदर्शी बैकग्राउंड) and lossless compression. Ideal for logos and web graphics.
• .gif (Graphics Interchange Format): Supports simple looping animations (चोरी-छिपे चलने वाले छोटे वीडियो/एनिमेशन). Limited to 256 colors.
• .bmp (Bitmap Image): Uncompressed, raw raster image created by MS Paint. Very large file size.
• .svg (Scalable Vector Graphics): Vector graphic format based on mathematical formulas; can be zoomed infinitely without losing sharpness or pixelating.

4. Audio, Video, and System File Extensions

Audio (ध्वनि / संगीत):

• .mp3 (MPEG Audio Layer III): The global standard compressed digital audio format.
• .wav (Waveform Audio): Uncompressed, studio-quality sound format used in Windows.
• .aac / .m4a: Advanced Audio Coding used by Apple and YouTube.

Video (चलचित्र / वीडियो):

• .mp4 (MPEG-4): The universal digital multimedia container for video and audio on the web and smartphones.
• .avi (Audio Video Interleave): Classic Windows video format developed by Microsoft.
• .mkv (Matroska Video): High-definition video container supporting multiple subtitle and audio tracks.

System & Executable (प्रोग्राम फ़ाइलें):

• .exe (Executable File): A runnable application program in Windows (e.g. setup.exe).
• .bat (Batch File): A script file containing a sequence of command-line DOS commands.
• .sys / .dll (System & Dynamic Link Library): Core Windows system files and shared library code.
• .zip / .rar / .7z (Compressed Archives): Containers holding compressed files to save storage and enable easy emailing.

Multiple Choice Questions

1. What is the default file extension of a document saved in LibreOffice Writer?

A. .docx B. .odt C. .ods D. .odp Answer: B Explanation: LibreOffice Writer saves text documents in OpenDocument Text format with the default extension .odt.

2. What is the default file extension of a spreadsheet created in LibreOffice Calc?

A. .xls B. .xlsx C. .ods D. .odt Answer: C Explanation: LibreOffice Calc uses the OpenDocument Spreadsheet format, saving files with the .ods extension by default.

3. Which image file format supports transparent backgrounds?

A. .jpg B. .bmp C. .png D. .txt Answer: C Explanation: PNG (Portable Network Graphics) supports alpha-channel transparency, making it the preferred format for logos, website icons, and transparent overlays.

4. What does the file extension .pdf stand for?

A. Public Document Format B. Portable Document Format C. Permanent Data File D. Printable Digital File Answer: B Explanation: PDF stands for Portable Document Format, developed by Adobe Systems to preserve document presentation and formatting across all platforms independently of hardware or software.

5. What type of file is represented by the .zip or .rar extension?

A. Audio recording B. Video clip C. Compressed file archive D. Device Driver Answer: C Explanation: .zip and .rar are compressed archive file formats that bundle one or multiple files into a reduced-size container for storage efficiency and network transmission.