File size should be one of the main concerns when placing images on web pages. A good rule of thumb is that the sum of all of the content on a Web page total less than 60K!

That certainly doesn't seem like a lot of memory...and it isn't. But if you use 72 dpi (dots {or pixels/ppi} per inch) as a maximum resolution, you will be surprised at how many images can "live" on a page.

Size also refers to the actual physical dimension of an image. If an image is larger than the screen in either direction the user will have to scroll to view all of it ... is this an appropriate size for the image??? Definitely NOT! One of the pet peeves of Web users is scrolling ... scrolling up and down is a neccessay evil but side-to-side is always a NO-NO!

This addresses the concern of designing for the "lowest common denominator". What is the smallest monitor size used by your Web audience. As a rule of thumb I design in a 600 pixel (8.333 inches) wide "page". This is also a printer friendly width! The content on this page is in a 600 pixel width table.