You might have seen the option to subset fonts when making PDFs either through your layout program or when making the PDF through Acrobat Distiller. So, perhaps you are wondering what does that option do, and will it affect the way my PDFs look on screen?
If you embed the whole font in the PDF, the person on the other end can make changes to it even if he didn't have your font, if he has the full version of Acrobat or another program with the capability of modifying PDFs. The file size of the PDF would also be bigger because you are embedding the entire font.
Subsetting Fonts
If you subset the font, the person who receives your PDF would need to have your same font in order to make changes to your PDF. The file size of the PDF would also be smaller because you are embedding only part of a font. When you subset a font, you usually just embed the characters you are using (obviously it depends on how you are subsetting your font). That's why somebody on another computer would have to have your same font in order to make changes.
Modification vs. View/Print
Don't get confused though: I am talking about how somebody else will be able to modify your PDF, not about how they can view it or print it. If you embedded your fonts properly and your fonts are not corrupted, then whether you subset the font or not will not affect the way somebody else can view or print your PDF.
Quick Reference
- Full Font Embedding = Larger file size
Recipient doesn't need the same font to view or edit the file - Subset Font Embedding = Smaller file size
Recipient doesn't need the same font to view but does need the same font installed in order to edit the file - No Font Embedding = Smallest file size
Recipient needs to have same fonts installed