How to install Fonts into Adobe Illustrator

You don't install fonts directly into any app, you add them to Font Book, or whatever font manager you're using. All fonts you install and activate are then available to all apps on your computer.

There's two ways with Font Book.

1) Create a new Font Set. Add your fonts. Done this way, the fonts you add are copied to the Fonts folder in your user account, and those are the fonts which are then activated. The originals can be removed if you want, though they should be kept as a backup.

2) Create a new Library Set. Add your fonts. With this method, the fonts are activated from where they currently are located, and not copied anywhere. Known as activating "in place".

I just dragged and dropped the downloaded ".tff" font files into in Font Book icon in theDock and a new window popped up and just click "Install Font" button.

That works, too. Sets are, more than anything else, just a way to organize your fonts by project. By dropping the font in, it should now be listed in one of the standard headings like "Computer".

The new fonts have automatically loaded into Adobe Illustrator CS3 without having to close it.

Better apps will see when fonts have been enabled or disabled without having to close and restart them. Microsoft Word (and likely the entire Office suite) does not.