When people say a file is stored “in binary,” they mean its contents are just a long sequence of 1s and 0s — but that description applies to literally every file on a computer, so the interesting question isn’t whether something is binary, it’s how those 1s and 0s get interpreted.
Every File Is Binary Underneath
At the hardware level, a hard drive or memory chip has no concept of letters, pixels, or musical notes — it can only store the presence or absence of an electrical signal, which is why every single file, whether it’s a text document, a photo, or a song, is ultimately just binary data.
So What Makes “Binary Data” Different From Text
The distinction people usually mean is narrower: a text file’s binary content follows a character-encoding standard like ASCII, so opening it in a basic text editor shows readable letters. A file described as “binary data” — like an image, an executable program, or a compressed archive — follows a different, often proprietary structure, so opening it in a plain text editor shows garbled symbols instead of anything meaningful.
How Programs Know What to Do With It
A program reading a file needs to know which interpretation to apply, which is usually signaled by the file extension or a short “header” of bytes at the very start of the file that identifies its format. A .txt file’s bytes are read as ASCII or Unicode characters; a .jpg file’s bytes are read according to the JPEG image format’s rules — the same underlying 1s and 0s would look meaningless if you swapped interpretations.
Why This Matters When Something Goes Wrong
This is also why opening the wrong file type produces nonsense instead of an error — a program forced to display binary image data as text will show unreadable symbols rather than a picture, because it’s applying the wrong decoding rules to data that was never meant to be read that way.
Seeing the Idea in Practice
You can see the basic principle firsthand with plain text, which is the simplest binary encoding to reason about. Our binary translator converts typed text into its raw binary form so you can see exactly what a text file’s “binary data” looks like before a text editor decodes it back into letters for you.
Examples of Binary Data
- Numbers: a whole number stored in 4 bytes can hold values up to about 4.29 billion (unsigned).
- Images: each pixel often takes 3 bytes (red, green and blue). A full HD screen of 1920 by 1080 pixels is 6,220,800 bytes before compression, which is about 6.2 MB.
- Audio: thousands of numbers per second, each describing the sound wave at that moment.
- Programs: instructions a processor can run directly.
Text vs Binary Storage of a Number
Stored as text, the number 255 is the three characters “2”, “5” and “5”, which take three bytes. Stored as binary data, it is the single byte 11111111. This is one reason binary formats are smaller.
Sending Binary Data Over Text Channels
Email and many web systems were designed for text. To send binary data through them, it can be converted with Base64, which represents the bytes using only letters, digits and a few symbols. The result is about one third larger than the original. You can try it with our Base64 Encode/Decode tool.
Compression and Binary Data
Because binary data often contains patterns and repetition, it can be compressed. ZIP, JPEG and MP3 all reduce size by encoding the same information more efficiently. The 6.2 MB image above usually shrinks to a few hundred KB as a JPEG.
Units for Measuring It
Binary data is measured in bytes and their multiples. To see how they compare, read bytes, KB, MB and GB explained.
Related Reading
For a deeper look at how those 1s and 0s map to actual values, see our guide on how binary code works, or for the file-format side of this topic, see our guide on what a binary file actually is.