Windows-based applications can use three different kinds of font technologies to
display and print text: raster, vector, and TrueType. 
                        ------  ------      --------
The differences between these fonts reflect the way that the glyph for
each character or symbol is stored in the respective font-resource file.

In raster fonts, a glyph is a bitmap that Windows
uses to draw a single character or symbol in the font. 

In vector fonts, a glyph is a collection of line endpoints that define
the line segments Windows uses to draw a character or symbol in the font.

In TrueType fonts, a glyph is a collection of line and curve commands
as well as a collection of hints. Windows uses the line and curve commands
to define the outline of the bitmap for a character or symbol in the
TrueType font. Windows uses the hints to adjust the length of the lines and
shapes of the curves used to draw the character or symbol. These hints and
the respective adjustments are based on the amount of scaling used to reduce
or increase the size of the bitmap.

Because the bitmaps for each glyph in a raster font are designed for a specific
resolution of device, raster fonts are generally considered to be device
dependent. Vector fonts, on the other hand, are not device dependent, because
each glyph is stored as a collection of scalable lines. However, vector fonts
are generally drawn more slowly than raster or TrueType fonts. TrueType fonts
provide both relatively fast drawing speed and true device independence. By
using the hints associated with a glyph, a developer can scale the characters
from a TrueType font up or down and still maintain their original shape. As
previously mentioned, the glyphs for a font are stored in a font-resource file.
A font-resource file is actually a Windows library that contains only data -
there is no code. For raster and vector fonts, this data is divided into two
parts: a header describing the font's metrics and the glyph data. A
font-resource file for a raster or vector font is identified by the .FON
filename extension. For TrueType fonts, there are two files for each font: the
first file contains a relatively short header and the second contains the actual
font data. The first file is identified by a .FOT extension and the second is
identified by a .TTF extension.

The OpenType font format is an extension of the TrueType font format, adding support
for PostScript font data. The OpenType font format was developed jointly by
Microsoft and Adobe. OpenType fonts and the operating system services which
support OpenType fonts provide users with a simple way to install and use fonts,
whether the fonts contain TrueType outlines or CFF (PostScript) outlines.

The OpenType font format addresses the following goals:
  broader multi-platform support
  better support for international character sets
  better protection for font data
  smaller file sizes to make font distribution more efficient
  broader support for advanced typographic control
  
OpenType fonts are also referred to as TrueType Open v.2.0 fonts, because they
use the TrueType 'sfnt' font file format. PostScript data included in OpenType
fonts may be directly rasterized or converted to the TrueType outline format for
rendering, depending on which rasterizers have been installed in the host
operating system. But the user model is the same: OpenType fonts just work.
Users will not need to be aware of the type of outline data in OpenType fonts.
And font creators can use whichever outline format they feel provides the best
set of features for their work, without worrying about limiting a font's
usability

OpenType fonts can include the OpenType Layout tables, which allow font creators to
design better international and high-end typographic fonts. The OpenType Layout
tables contain information on glyph substitution, glyph positioning,
justification, and baseline positioning, enabling text-processing applications
to improve text layout.

As with TrueType fonts, OpenType fonts allow the handling of large glyph sets using
Unicode encoding. Such encoding allows broad international support, as well as
support for typographic glyph variants.