What is the difference between TrueType®, PostScript® and OpenType™ fonts?

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There are three types of fonts you need to be aware of: TrueType, PostScript and OpenType. They are stored in different directories on the different operating systems.

PostScript Fonts
There are generally two main components to PostScript typefaces. The first file contains the actual PostScript typeface itself and is often called the “binary” or “printer” file. The second file contains the typeface’s complete name, the spacing characteristics (font metrics) and information to help the computer display the typeface on the screen and for printing the font. Both files must be submitted.

PostScript typefaces are the preferred typeface format for use in publishing.

Macintosh PostScript

There are at least two parts to this font: a Screen font and a Printer font. Both files must be submitted and there may be more than one Printer font.

Screen fonts will be in the Suitcase. Inside the Suitcase are files that have icons that look like pieces of paper with one A on them.

Mac PostScript font Suitcase

Printer fonts can take a variety of forms. One file is needed for each instance of the font.

Adobe printer fonts viewed by icon look like this: Mac Adobe printer font

Other printer fonts could look like: Mac other printer font

Note: PostScript “printer” files usually have abbreviated file names, but are typically easy to interpret. The first five characters are the abbreviated typeface name, followed by one or more three-character typeface attributes. Some examples of these three-character typeface attributes are “Bol” (bold), “Ita (italic), “Rom” (roman or plain), “Con” (condensed)”, “Obl” (oblique, similar to italic), “Ser” (serif) and “San” (sans serif).

Windows PostScript fonts

There will be at least two parts to this font: an Outline font (.pfb file) and a Font Metrics (.pfm) file. Both files must be submitted.

The Postscript font files will look like this: WIndows PostScript font

Note: Since most PostScript typeface files still follow the DOS 8.3 naming conventions, the actual typeface file names could be highly abbreviated and the file names may have little resemblance to the actual typeface name. Without ATM (Adobe Type Manager), finding the correct files for a specific PostScript typeface might be a complex guessing game. Consult the documentation that was included with the typeface package, if this documentation is unavailable, the typeface manufacturer’s web site may help you identify the correct files.

OpenType Fonts
OpenType fonts are cross-platform compatible making it easier to share files across operating systems. Font management is simpler since there is just one file involved. An OpenType font file contains all the outline, metric and bitmap data in one file. It can contain TrueType (.ttf extension) or PostScript (.otf extension) font data and uses ATM to render the font on-screen. Adobe® InDesign® and Adobe® Photoshop® support OpenType which allows them to use the expanded character sets and layout features.

PostScript OpenType Font
OpenType font Mac

TrueType OpenType Font
OpenType Font TrueType Windows

TrueType Fonts
Truetype fonts only require one file to be submitted but a separate file needs to be submitted for each instance of the font. For example, a different file is needed for normal, bold, italic, bold italic, etc. TrueType typefaces are generally intended for business office use and can be less reliable for publishing applications. Only use TrueType typefaces when the typeface is unavailable in PostScript format.

Macintosh TrueType fonts

Mac Times font fileA Macintosh TrueType font will consist of one file which has an icon that looks like a piece of paper with 3 A’s on it or the different instances (bold, italic, bolditalic, etc.) of a font will be grouped in a Suitcase.

 Mac Times TrueType font

The single files or the suitcase (if applicable) need to be copied to your disk and submitted.

Mac dfontOS X only
A dFont or data fork TrueType font consists of one file and only works with OS X apps.

NOTE: Mac OS System 8 and greater include some TrueType typefaces that are equivalent to many of the PostScript typefaces. The Macintosh system will attempt to use TrueType fonts whenever possible for screen displays, even if equivalent PostScript typefaces are available. Conversely, a PostScript printer will use PostScript typefaces whenever possible for printing your pages. It is for this reason that the computer should not have BOTH a TrueType AND a PostScript version of the same typeface installed at the same time. In these cases, it is better to remove the TrueType versions and force the Macintosh to use the PostScript versions. This will help avoid character and line spacing problems when you print your pages. It also could help avoid some type-spacing proof corrections.

Windows TrueType fonts

A TrueType font will consist of one file and each instance (bold, italic, bolditalic, etc.) will have its own file. All the different files need to be copied to a disk and sent with your pages. The icons will look different depending on the view.
Windows TrueType font

For more information on where fonts reside on your computer, check out Where are my fonts? 

For installation instructions, refer to:
How do I install fonts in a Windows operating system? or
How do I install fonts on a Mac running OS 9.x or below? or
How do I install fonts on a Mac running OS X?