Digital photos, direct from the digital camera, or scanned photographic prints create large photo files. These large files contain information which is necessary and essential for print reproductions. These large files contain way more information than needed for screen view on one's computer monitor.

So if your intended output is for the recipient to view the photo(s) on their computer only, and you don't want to send monster files which burden both sender and receiver, the work to do in advance of sending the photo is called "optimization."

Many photo editing programs have this feature installed, somewhere, so it is simply to find it. In photoshop, for example, one goes to File-Save For Web, and you are taken to an area where you can determin to what compromise of visual quality and size for the benefit of small file size you are willing to accept.

Some photo editing programs use "send by email" or some such name to serve as a euphemism for optimization.

Once you have optimized, you have a kinder, gentler file for sending across email.

This is a simplification of the process, and an introduction. There are many other criteria that we at Crestone Creations take into account for saving for the web, such as applying unsharp mask, giving a stroke border, etc., but hopefully this will get you going.