Manage Fonts with Font Book in Mountain Lion
Font Book in OS X Mountain Lion lets you view your installed fonts, install new fonts, group your fonts into collections, and enable and disable installed fonts. As usual, you find the Font Book application in the Applications folder at root level on your hard disk.
Other ways you can install new fonts are to choose File→Add Fonts or press Command+O. A standard Open dialog allows you to select a font or fonts to be installed.
Note that, by default, new fonts are installed in your Home folder’s Fonts folder, which is inside your invisible Library folder (Users/Home/Library/Fonts). You can change the default installation location in the Font Book preferences pane (Font Book→Preferences or Command+,).
To view a font or font family, click its name in the Font list. Click the disclosure triangle before the name of a font to see all the variants that are installed.
To change the size of the viewed font, click the triangle next to the font size (18 in the figure) in the top-right corner of the Font Book window and choose a new size from the drop-down list that appears, or type a different number where the number 18 appears, or move the size slider — the white dot and gray line that run along the right edge of the window — up or down.
To disable a font so it no longer appears on any applications’ Font menus, choose Edit→Disable or click the Disable button (the check mark in a square button) at the bottom of the window.
To enable a previously disabled font, choose Edit→Enable or click the Enable button (same as the Disable button).
Mountain Lion’s Font Book looks out for your best interests; it won’t allow you to disable or delete any fonts required by Mountain Lion — including (but not limited to) Lucida Grande, Helvetica, and Helvetica Neue.