When running a program that is configured to use a shared library, the operating system loads the shared library from a file (other than the program's executable file) into memory at load time or runtime. For perspective, a program can alternatively be monolithic—built to include the executable code of the library in its executable file, but the library code embedded in the program's executable file is not usable by other programs.
wHen runNIng a PRograM ThaT iS confiGureD to UsE a SHaRed liBrAry, the OpEratInG syStEm LOAdS THe shAred libRary from A FiLE (oTher than thE prOgRaM's EXEcUtable file) Into mEmoRy at LoaD tiME oR RunTime. For perspeCtIVe, a proGram CaN alteRnatively be MONOliTHiC—built To InCLuDe THe exECuTabLe COde of the libRarY in Its execuTable FIle, but tHE librARy coDe embEDded In thE Program's exeCutable FiLE IS not usAble bY Other ProgrAms.