Metadata, SEO, and SEM

Images in web pages are usually JPG or GIF files. JPEGs are better for photos and images with lots of clor and detail. GIFs are used for icons and simpler images. Both JPGs and GIFs are incorporated in HTML using the img tag.

At a minimum you can use a line like:
  <img src="photo.jpg" />

It's better to give the browser the size of an image so it can display it quickly:
  <img scr="http://www.myURL.com/photo.jpg" width="50" height="25" alt="mouse-over text" title="instead of alt tag" />

The alt text is displayed when the mouse hovers over an image. Firefox does not display mouse-over text. Firefox uses the title tag instead. The alt tag is also used for disabled surfers who rely on text or speech instead of visual images. The alt and title tags should be part of your SEO strategy. Search engines evaluate them when crawling your site.

The hspace and vpace tags determine how much white space is around your image horizontally and vertically. The border tag sets the border width around an image. The align tag (left, middle, right) determines a graphic's position relative to other elements in the page.

In the interest of full disclsure, the align, border, hspace, and vspace attributes were deprecated in HTML 4.01 and are not supported in XHTML 1.0 Strict DTD. They still work but are better handled in CSS.
  <img scr="skybox.jpg" width="50" height="25" alt="mouse-over text" title="instead of alt tag" hspace="0" vspace="0" border="0" align="left" />

Name your graphic file with search engines in mind. 173.jpg gives no clue about an image. West-Seattle-map.jpg or acpuncture-chart.jpg are much better because the filenames tell the search engines what they're "looking at". Hint: Google likes hyphens as word seperators, therefore little-red-wagon.gif is better than littleredwagon.gif.