While there are many different file formats that can be used for fonts, some are easier to install and use than others. TrueType fonts, which use the file extension *.ttf and OpenType fonts, which use the file extension *.otf, are among the most common — as well as the easiest to use. Many font directories that you might find fonts through tend to use these two formats — which work on both Macs and PCs.
There are two other formats that can be somewhat common, the Generic Font file (*.fon) and the Windows Font file (*.fnt). While most computers will be able to add Generic Font files fairly easily, Windows Font files will not work on Macs.
In general, as long as you use a Mac or Windows computer, TrueType and OpenType fonts will be the best choice.
Not all fonts are complete: some include a full set of symbols and accented characters, as well as the standard letters and numbers. Others, however, will only provide letters and numerals — and sometimes not even that. Depending on the original purpose the font was developed for, it may only include upper case letters or be missing numbers. That doesn’t necessarily make a font a bad choice, as long as you’re only planning to use it for titles or accent text. But if you need a font that you can set longer blocks of text in, or you need specific symbols, it’s important to look at the font’s character map before downloading it.
Most sites that offer fonts as free downloads or as purchases offer you the ability to look at the font’s character map before you download it. Character maps usually display the standard letters and numbers of a font first, and then display symbols and accented letters farther down. As long as you know the specific character you need, you should be able to find it. If no character appears in the space where your necessary letter or symbol should be, you may want to skip that font.
Some character maps will display boxes or non-characters in the map to fill up space for missing characters. It’s important to double-check that an actual character is listed, rather than a space-holder.
Usage and Licenses
Some free fonts have limitations on what they can be used for: their creators release them for free under a license that only allows for non-commercial use. Using a font not licensed for commercial use can lead to legal issues. It’s important to check the license under which the font is available.
You’ll find that some font directories that offer free fonts will list individual license information with each font. Others will simply set a licensing policy for all fonts available on the site. Either way, it’s important to read the licensing agreement — you legally agree just by downloading the font — before making your choice.