Acrobat automatically installs Adobe Type Manager (ATM) and special "substitution fonts" during the Acrobat installation process. It is this utility and these fonts which enable you to choose not to include fonts, and still allow the document to look pretty much like the original document with the correct fonts.

In addition to this issue, there are many other font considerations to keep in mind when designing documents that will eventually end up in PDF form.

I've found that I choose to embed fonts more than 90 percent of the time, only choosing not to embed when I'm desperately trying to keep file sizes to a minimum. Not that fonts really add that much overhead, but 10K here and there can quickly add up to several megabytes.

When to embed
Always choose to embed fonts (via the Distiller or PDF Writer options) in the following situations:

• When the document is being used for proofing (appearance, not text).
• When the document contains text such as part of a logo that must be a certain font.
• When the fonts are decorative, graphical, or symbol-based (such as Zapf Dingbats or Carta).
• When the document needs to be used as a substitute for the original document.
• When the document is being sent to a service bureau or other place for final output.

The images below show the difference between a PDF with embedded fonts (Figure 1), and without embedded fonts (Figure 2).

Figure 1 - A PDF of the first page of this chapter (from the previous edition of this book) shown with fonts embedded.

Figure 2 - A PDF of the first page of this chapter (from the previous edition of this book) shown with fonts not embedded.