There are lots of ways you can view photos on a web page
- just plainly, or in a slideshow perhaps, or displayed small
then enlarging or opening in another window when you click
on them or on mouseover - it's really a matter of taste and
what you intend the viewer to get out of the photo visual experience.
Click on the links below to see a few of the methods I use regularly.
Thanks to all the individual independent developers who made
some of these possible in shared software.

As a matter of procedure, unless there are large amounts of pictures or photos to get through I generally optimise images (make the size of the image as small as is practical)
for use on web pages so that the page loads as fast as possible. and this is a service I offer free of charge but is not included in slide shows and presentations

It's worth bearing in mind that if your customers really know all the tricks, they'll be able to download your images. Should you need to prevent the use of your images without your permission it would be as well to watermark them when showing in enlarged forms.