What is the difference between accessor and mutator methods?

Question

How are accessors and mutators different? An example and explanation would be great.

Answer 1

class foo
{
    private:

        int a;
    public:
        int  accessA() const { return(a);}
        void mutateA(const int A) { a = A;}
}

Also known as getters and setters and probably a dozen other terms.