Dynamic libraries, also known as shared libraries, are collections of code and data that programs can use at runtime. Unlike static libraries, which are included in the final executable, dynamic libraries are loaded into memory when needed, allowing multiple programs to share the same library without duplicating code. This can save disk space and memory. Dynamic libraries are commonly used in operating systems like Windows and Linux. They typically have file extensions such as .dll for Windows and .so for Linux. This modular approach enables easier updates and maintenance, as developers can modify the library without needing to recompile the dependent programs.