认识
Most typefaces include variations in size (e.g., 24 point), weight (e.g., light, bold), slope (e.g., italic), width (e.g., condensed), and so on. Each of these variations of the typeface is a font.
组成
字体文件格式
pfb（Printer Font Binary）
PFB File – What is it and how do I open it?
# fc-list | grep pitch -i /usr/share/fonts/X11/Type1/c0419bt_.pfb: Courier 10 Pitch:style=Regular /usr/local/share/fonts/Courier 10 Pitch Regular.otf: Courier 10 Pitch:style=Regular /usr/share/fonts/X11/Type1/c0611bt_.pfb: Courier 10 Pitch:style=Bold Italic /usr/local/share/fonts/Courier10PitchBT-Roman.otf: Courier 10 Pitch:style=Regular /usr/share/fonts/X11/Type1/c0582bt_.pfb: Courier 10 Pitch:style=Italic /usr/share/fonts/X11/Type1/c0583bt_.pfb: Courier 10 Pitch:style=Bold
otf（OpenType Font）
OTF vs. TTF Fonts: Which Is Better? What’s the Difference?
ttf（TrueType Font）
TrueType – Wikipedia
构建
访问 Programming Fonts – Test Drive 站点，以查看并下载自己喜欢的字体。
https://www.programmingfonts.org/
应用
macOS 使用什么字体？
The font you see in most places on Mac OS X is Lucida Grande, it is the system font in OS X 10.1 Puma to 10.9 Mavericks. Mac OS 1-7 used Chicago, then Mac OS 8 and 9 used Charcoal.
The most recent additions are Helvetica Neue (OS X 10.10 Yosemite) and San Francisco (OS X 10.11 El Capitan through Mojave)
参考
What’s the font in Mac OS X’s GUI?