void * :

• is a pointer that can hold the address of any data type.

unsigned char :

• data type used to represent a character that can only take non-negative values (0-255), if u assign to it a negative value it will overflow to the maximum

type casting :

• a way to convert a variable from one data type to another, its used to ensure that a variable its treated as a different type than its original type for a specific operation or context.

size_t :

• an unsigned integer data type that is used to represent size of objects.

static functions :

• functions that are visible only to other functions in the same file.

File descriptors :

• In Unix systems, a file descriptor is a small positive integer used as a reference to an open a file in a process. A process is a currently running program.
• From the OS’s POV, a file isn’t only a text file, a file can be also a directory or even another type of I/O resource