Consider another scenario: you know the type of data you want a variable to store, as well as its name, but not its value. The value will be computed and assigned somewhere else, but you still need to declare the variable at the top of the script.
This situation is perfect for a type-only declaration:
int currentAge;
Only the type (int) and unique name (currentAge) are defined, but the statement is still valid because we've followed the rules. With no assigned value, default values will be assigned according to the variable's type. In this case, currentAge will be set to 0, which matches the int type. Whenever the actual value is available, it can easily be set in a separate statement by referencing the variable name and assigning it a value:
currentAge = 32;
At this point...