Fat Binary

A fat binary (or multiarchitecture binary) is a computer executable program which has been expanded (or "fattened") with code native to multiple instruction sets which can consequently be run on multiple processor types. The usual method of implementation is to include a version of the machine code for each instruction set, preceded by code compatible with all operating systems which executes a jump to the appropriate section. This results in a file larger than a normal one-architecture binary file, thus the name.

The use of fat binaries is not common in operating system software; there are several alternatives to solve the same problem, such as the use of an installer program to choose an architecture-specific binary at install time, distributing software in source code form and compiling it in-place, or the use of a virtual machine (such as with Java) and Just In Time compilation.