If you insert pictures (photos, logos, etc.) into a document, it's usually a good idea to compress them so that they do not take up too much room in your document. The exception to this is if you intend on sending the document to a commercial printer for reproduction.
In most cases, the selections indicated above are appropriate. If
the document will be primarily used online or viewed in Web pages, choose
the Screen option. The E-mail option will offer less quality
but a smaller file size.