Once you start downloading fonts, you'll soon notice that there are often more than one kind of font format included. Fonts can be confusing since there are so many different font types. Once you've finally got over the most difficult thing, actually choosing a font, you're slammed with another decision immediately. How can you decide which format you should download? Well, the first step is understanding the different types of fonts. The differences between font formats can get pretty technical, so we'll just keep this as a simple guide.
There are three different kinds of font formats - bitmapped, stroke, and outlined. Bitmapped fonts have pretty much fallen out of favor, since they aren't scalable, but outlined fonts are. Stroke fonts use a series of lines to define the size and shape of the lines in the specific face which will together create the appearance of the particular glyph. Bitmapped fonts are raster and outlined fonts are vector using Bézier curves. All the font formats that we'll talk about are outline font formats.
Four of the most commonly talked about font formats are PostScript, TrueType, OpenType, and Web Open Font Format.
PostScript fonts were created by Adobe. They have two different parts, one that contains information for printing, and the other that's used to display the font on the screen. PostScript fonts make it possible for really high quality printing. A drawback to them is that they're not cross-compatible, so there are different versions for Macs and PCs. PostScript fonts are also often referred to as Type 1 Fonts. Since the creating of OpenType fonts, the use of PostScript fonts has dwindled significantly.
TrueType is a font format that was developed by Apple and was eventually licensed to Microsoft. They only require one file, but a separate file needs to be added for each instance of the font. Which means you'll need a different file for normal, italic, bold, bold italic, etc. TrueType typefaces are usually used in a business office since they can be a little unreliable for publishing. TrueType fonts work well with Microsoft Office. For a while TrueType fonts worked really well with PostScript fonts, meaning that the TrueType fonts would be used for screens, and PostScript for printing purposes.
OpenType is a newer font type build on the TrueType format that supports more advance typesetting features like smallcaps, ligatures, and alternatives inside the font instead of separately. It was intened it repalce TrueType fonts. OpenType fonts were initially created by Adobe and Microsoft and uses the Unicode standard for character encoding.
A great thing about OpenType fonts is that they're compatible cross-platform, so it's easier to share files to different operating systems. These types of font files contain all the outline, metric, and bitmap data for the font in one file, which is a great time saving featured.
Sometimes OpenType fonts end in .otf but, confusingly, they can also end in .ttf. These fonts are also well suited for desktop publishing software like InDesign since they're compatible with print workflows.
Web Open Font Format (.woff)
Web Open Font Format (WOFF) is a font format that's used on web pages. It works just like TrueType and OpenType, but since it's compressed it'll make your content download more quickly.
Currently all browsers support WOFF. Often font vendors don't want to license their TrueType or OpenType format fonts for web use, but they'll license WOFF. A webfont is created in such a way that it's possible to use the CSS @font-face declaration. A webfont, however is a font that includeds the WOFF file, asw well as a TrueType files, SVG file, and EOT file. The different files are necessary for cross-browser compatibility.
Hopefully by now you're understanding the different font formats and you'll certainly be able to find the right format for you and your current project!