• OpenType Font is a new standard font created by Adobe and Microsoft. It’s a truly cross platform font. ~.otf
• TrueType (TT) Font is an outline font standard developed by Apple in the late 1980s as a competitor to Adobe’s Type 1 fonts used in PostScript. TrueType has become the most common format for fonts on both the Mac OS and Microsoft Windows operating systems. ~.ttf
• Type 1 font was introduced by Adobe in 1984 as part of the PostScript page description language. When the first laser printer to use the PostScript language, the Apple LaserWriter, was introduced.
• Type 3 font, also known as PostScript Type 3 or PS3, T3 or Adobe Type 3, was introduced by Adobe.

When you begin your font research, you need to preview fonts in the font menu.
Let’s check the preference first.
Illustrator > Preference > Type to make sure the Font Preview box checked.
When choosing fonts, always find fonts from the Character panel.

There is a powerful feature in Illustrator called Find Font
Go Type > Find Font to find fonts in your computer system.