Or maybe more explicitly. (In SQL) NULL is a database field value, indicating missing/omitted data. (In C) A NULL-pointer is a pointer made by converting the constant 0 to a pointer and indicates that the pointer doesn't really point to anything (In ASCII, and in C) NUL is the character value of 0, which is often used to terminate strings. To have something NULL-terminated would be to have a list of pointers, the last one being a NULL-pointer.