This text is aligned with the top of the image but the text is allowed for flow around the left of the image. The alt Option Not all browsers support images. Also, images take a long time to load over slow lines, so some users turn image loading off. In this case an icon will be displayed in the place of the image. Since this does not tell you anything about the image it is desirable that some descriptive text appear which tells what the image is.
Many browsers attempt to display as much information as they can as quickly as they can.
Since a browser must request an HTML page and all graphics that page contains it can put the page up before the graphics arrive. But, the size of a graphic is contained in the graphic file. So, the display must be deferred. If the browser knew in advance just how large the image is it could immediately draw the page leaving holes for the graphics. This is the function of the size options in the img tag.