The LD_LIBRARY_PATH environment variable contains a colon separated list of paths that the linker uses to resolve library dependencies of ELF executables at run-time. These paths will be given priority over the standard library paths /lib and /usr/lib. The standard paths will still be searched, but only after the list of paths in LD_LIBRARY_PATH [...]

The ldd command allows you to view detailed information about library dependencies of dynamically linked programs and other shared libraries. ldd uses the runtime linker ld.so which reads the ELF formatted executable to generate the output. It is a helpful tool to have at your disposal when debugging broken programs.
Here ldd examines the ‘ls’ executable. [...]