Why is compiled code typically not portable from one platform to another?

Compiled code is typically not portable between platforms due to differences in hardware architecture, operating systems, and system libraries. Each platform may have its own specific instruction set, memory management, and system calls, which can lead to binary incompatibilities. Additionally, compilers optimize code differently for various environments, making the generated binaries incompatible. As a result, code often needs to be recompiled or adjusted to run on different platforms.