How does resolution relate to the size of an image?

What will be an ideal response?

A bitmap graphic is simply a collection of data. Unlike a printed photograph, a bitmap graphic has no fixed physical size. The size at which a bitmap graphic is displayed or printed depends on the density as well as the resolution (dimensions) of the image grid. Imagine that each bitmap image and its grid come on a surface that you can stretch or shrink. As you stretch the surface, the grid maintains the same number of horizontal and vertical cells, but each cell becomes larger and the grid becomes less dense. As you shrink the surface, the grid becomes smaller and denser. The graphic retains the same resolution (grid dimensions) no matter how much you stretch or shrink the graphic's physical size. This concept of stretching and shrinking without changing resolution is important for understanding what happens when bitmaps are displayed and printed. The denser the grid, the smaller the image will appear. The density of an image grid can be expressed as dots per inch for a printer or scanner, or as pixels per inch for a monitor.