Image tag optimization

It Is also called alt tag. We must add image tag to any image for explaining to users regarding the image. Some times images don’t get opened but image tag will explain about that image and user will not get confused.
Read this for more: http://www.spunkyjone s.com/image-alt-tag/
Canonical / 404 Implementation
Canonical error means 404 page not found error. We must redirect (called 301 permanent redirection) those pages which contains canonical error to some other page of the site or to the home page.
http://groups.google.co m/group /google_webmaster_hel p-indexing /browse_thread/thread /1d93fa52e2a08b8a /3adde832f465bd0e?ln k=gst&q=