I believe the name has something to do with making a distinction between:
- code for humans -- source code
- code for machines -- object code
Object files contain:
- Header information: overall information about the file, such as the size of the code, name of the source file it was translated from, and
creation date.
- Object code: Binary instructions and data generated by a compiler or assembler.
- Relocation: A list of the places in the object code that have to be fixed up when the linker changes the addresses of the object code.
- Symbols: Global symbols defined in this module, symbols to be imported from other modules or defined by the linker.
- Debugging information: Other information about the object code not needed for linking but of use to a debugger. This includes source file
and line number information, local symbols, descriptions of data
structures used by the object code such as C structure definitions.
Source: here
