Font file:
Contain one or more fonts that can be accessed by Operating system and application.
Most modern fonts are stored in either Open type or True type format by Macintosh and Windows.

Difference between Type face and Font file?
Type face is a particular design of type.
Font is a type in a particular size and weight.
 
File extension:
Commonly used fonts.
1. OTF:
Open type font.
Developed by Adobe and Microsoft.
Font can be resized without losing quality.

2. TTF:
True type Font.
Developed by Apple.
Font can be resized without losing quality and looks same when printed as it does on screen.

3. FNT:
Used by windows Operating system.
Large in size replaced by OTF and TTF.

Characteristics of Font:
Weight.
Slope.
Width.


Weight:
Ultra light to extra bold.