The image below should be 8.8cm wide and 5.9 cm high (about as wide as a business card):

The image below should be nearly as wide as the window (depending on your user style sheet) and resize when you resize the window:

The image below should be half as wide as the one above and resize when you resize the window:

MMMMMMMMMMMMMMM The image below should be 15em, i.e., about as wide as these 15 M's:

The image below should be 100px square:

The image below should be 144px wide and 96px high:

The image below should be normal size (72 x 48 px), but be centered:

There should be exactly 5 images on the next line (and 2 on the line below), no matter how you resize the window: