Shared object files streamline programs by providing information applications need to do their jobs, but that don’t have to be part of the application itself. To find out which of these files a Linux command calls on, use the ldd command.
What is a shared object file?
Shared object files (designated as .so) are libraries that are automatically linked into a program when the program starts, yet exist as a standalone files. They contain information that can be used by one or more programs to offload resources so that any program calling a .so file doesn’t itself have to actually provide all the needed tools. These files can be linked to any program and be loaded anywhere in memory.
Source:: Network World – Data Center