Why does a programming language need keywords?

Question

For example (in C):

int break = 1;
int for = 2;

Why will the compiler have any problems at all in deducing that break and fo

Answer 1

The compiler would have problems if you write something like this:

while(*s++);
return(5);

Is that a loop or a call to a function named while? Did you want to return the value 5 from the current function, or did you want to call a function named return?

It often simplifies things if constructs with special meaning simply have special names that can be used to unambiguously refer to them.