The MIME type binary/octet-stream is used to denote the presence of binary files. The category for this MIME type is "binary".

Binary files usually carry the extension BIN. A binary file by its very nature may contain any type of data that has been encoded in binary form so that it can be stored and processed on a computer. One example of such a file would be computer document files that contain formatted text. Some binary files may contain text without any formatting. This text is thus visible without the use of any parsing applications and is called plaintext.

In cases where a program is being downloaded without any installer, the resultant data can be called program binaries. These are different from source codes. Program binaries are common in Linux where they are used for installing the downloaded program.

Binary files are structured in sequences of bytes, where each byte is made up of 8 bits. This is foundation of all binary structures. Binary sequences are usually meant to be interpreted as something more than just plaintext. For example, compiled applications (objects) are often referred to as binaries by computer software programmers.