height

• Specifies the intended height of the image in pixels (can be a percentage of height available)
• Should be included if known

width

• Specifies the intended width of the image in pixels (can be a percentage of width available)
• Should be included if known

• If both given, allows browser to reserve screen space for the image before it has arrived over the network
• Speeds up presentation

Styling attributes width and height also apply.

<p>The following image is of a happy face image defined in the 
gif image format:
<img src="face.gif" width="48" height="48" alt="animated happy face" />.
The image element is a character-level or inline element which means
that it appears like a rather large letter or word in the middle of 
the paragraph. Character-level elements form part of the text flow 
within the paragraph. Control of the image's position is usually
done with a style sheet.</p>