Explain instance variables. Give an example.

Variables that are declared inside a class without using the keyword 'static' and outside any member methods are termed instance variables. Each object of the class gets its own copy of instance variables. For example, in the below class:

class Cuboid {
    private double height;
    private double width;
    private double depth;
    private double volume;

    public void input(int h, int w, int d) {
        height = h;
        width = w;
        depth = d;
    }

    public void computeVolume() {
        volume = height * width * depth;
        System.out.println("Volume = " + volume);
    }
}

height, width, depth and volume are instance variables.