● Relocatable object file (.o file)○ Code and data that can be combined with other relocatable object files to form executable object file■ Each .o file is produced from exactly one source (.c) file● Executable object file (a.out file)○ Code and data that can be copied directly into memory and then executed● Shared object file (.so file)○ Special type of relocatable object file that can be loaded into memory and linked dynamically, at either load time or run-time