TrueType
	Type 1
	Type 3
	Composite fonts (Type 0): both Type 1 (CIDFontType0) and TrueType (CIDFontType2) are supported.
	OpenType: From PDF 1.6 onwards, OpenType fonts can be stored directly in PDF files. In prior releases OpenType fonts are embedded as either Type 1 or TrueType fonts. The ability to embed OpenType directly was added for the forms capabilities of PDF, it offers no immediate advantage for prepress users.

By preference any fonts that are used in a layout are also included in the PDF file itself. This makes sure that the file can be viewed and printed as it was created by the designer. There are two mechanisms to include fonts in a PDF:

	Embedding – A full copy of the entire character set of a font is stored in the PDF.
	Subsetting – Only those characters that are actually used in the lay-out are stored in the PDF. If the “$” character doesn’t appear anywhere in the text, that character is not included in the font. This means that PDF files with subsetted fonts are smaller than PDF files with embedded fonts. For subsetted fonts, the font name is preceded by 6 random characters and a plus sign.

Embedding Fonts
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

In our PDF Compressor product, you can use -subsetfonts parameter to subset fonts in PDF file,

pdfcompressor.exe -subsetfonts C:\in.pdf C:\out.pdf

You can use following command line to embed all fonts into PDF file,

pdfcompressor.exe -embedallfonts C:\in.pdf C:\out.pdf

You can use following command line to embed all Windows fonts and into PDF file, and subset fonts to reduce PDF file size,

pdfcompressor.exe -winfont -embedallfonts -subsetfonts -compressfonts C:\in.pdf C:\out.pdf