Dynamic initialization is that in which initialization value isn't known at compile-time. Its computed at runtime to initialize the variable.
int f(); //some function int a = 10 ; //static initialization int b = f(); //dynamic initialization That is, static initialization involves constant-expression, while dynamic initialization involves non-constant expression.
Objects with static storage duration (3.7.1) shall be zero-initialized (8.5) before any other initialization takes place. Zero-initialization and initialization with a constant expression are collectively called static initialization; all other initialization is dynamic initialization.