Truly I say to you, Till heaven and earth come to an end, not the smallest letter or part of a letter will in any way be taken from the law, till all things are done.
Matthew 5:18 (BBE)
A font is a specific size and style of type within a type family [WordNet-Online]. Your system came with many fonts preinstalled but there are many, many more. There are tens of thousands of font families and perhaps hundreds of thousands of individual fonts (nobody really knows for sure).
The de-facto standard for decades, TrueType (TTF) remains the most popular scalable computer font format for display on the screen and for printing. Increasingly replacing TrueType is the OpenType (OTF) format, with more advanced typesetting features, better support for international character sets and smaller file sizes.
Finally, there is the Web Open Font Format – WOFF and WOFF2 – only readable by web browsers. A sub-set (or kind) of OpenType fonts are Variable fonts – these too are also only readable by web browsers.
In C4C Ubuntu, the Font Manager and Font Viewer work together to make font management simple
The Font Manager allows the average user to easily display, sort, search, organize and install a few thousand fonts
The Font Viewer allows the preview of individual fonts with a drag and drop interface. The Font Viewer allows installation of fonts as well.
The Raleway Black Italic font from The League of Moveable Type was previewed and installed
Thousands of fonts are available on the Internet. There are many, many websites that specialize in Fonts. Commercial pay-for fonts to absolutely no-restrictions public domain fonts and everything in between.
Just because a font (or font family, or font collection) is free, doesn’t mean it’s not copyrighted. Most fonts come with some sort of license. And though that license may give you unrestricted use of the font, many don’t.
Commercial fonts (and even many non-commercial fonts) come with a EULA; an End User License Agreement. Some of those EULAs have restrictions on your use of the fonts you may never have thought of.
FONT LEGALITIES Read The Law on Fonts and Typfaces at crowdSPRING, What Is a Font License? (And Do I Need One?) on Design Shack, and Everything you want to know about using fonts legally (but didn’t know to ask) on Odd Moxie.