A pointer is a variable that stores the memory address of another variable. It is used for dynamic memory allocation, passing parameters by reference, and efficient array handling.

Stack memory is used for static memory allocation and is managed by the CPU, whereas heap memory is used for dynamic memory allocation and is managed by the programmer. Stack allocation is faster, while heap allocation provides greater flexibility.

A 'struct' allocates separate memory for each member, while a 'union' allocates a single shared memory space for all its members. 'struct' is used when each element is unique, while 'union' is used to save memory when only one data type is used at a time.

Memory management in C is done using functions like malloc(), calloc(), realloc(), and free(). These functions allocate and deallocate memory dynamically at runtime.

The 'static' keyword in C is used to control the scope and lifetime of variables and functions. A static variable retains its value between function calls, while a static function is only visible within the file in which it is declared.

A segmentation fault, also known as a segfault, is a specific kind of error caused by accessing memory that the program is not allowed to access. It is often caused by dereferencing a null or uninitialized pointer, accessing memory out-of-bounds, or modifying read-only memory.