Some browsers accept the plain desktop font formats TrueType .ttf or OpenType .otf, but most font foundries denying the linking of desktop font formats. Of course they don’t want their fonts spreading around the net without proper paid licenses. You have to respect that.
Some free fonts coming with an Open Source like license and can be linked this way. But this has several bad consequences. Not all browsers support these font formats. The formats are meant for desktop usage, the fonts are big. Sometimes you need only a portion of the font data, so it would be wise to use the parts you need only to spare bandwidth.
Besides the desktop font formats there are the online font formats called web fonts or webfonts. I prefer and use webfonts like the term website.
.eot for Mircosoft Internet Explorer browsers
.woff the preferred and featured format by Mozilla, supported by Firefox 3.6 and Google Chrome 8
.svg/.svgz supported by iPad and IPhone browsers
.ttf (.otf) the plain desktop format supported by all current versions of Safari, Opera, Firefox and Chrome
But how to generate or convert these optimized webfont formats?
Fontsquirrell @fone-face generator
The Fontsquirrel converter is one of the best converters on the net. It’s also an generator, because it can rescale, re-hint and subsets the font data, optimizes the metrics, generates sample html files and converts to all needed webfont formats like .eot .woff .ttf .svgz .svg and Cufón.
Fontsqirrel can analyse the OpenType font feature code and can replace for example the lower case letters with their corresponding small caps in the final webfonts and many more. Of course this works on fonts only with have these feature code on board. A free sample you can try is Charis SIL. The Fontsquirrel generator can drastically reduce the file size by subsetting the fonts so only parts needed will be in the final webfonts.
sfnt2woff was the first converter for the .woff format. It’s available including source code. Not user-friendly!
Weft is the Microsoft .eot Generator. It has some unique features like URL binding and additional compression. Not user-friendly! Windows only!
Eot-fast is like its name a quick and painless .ttf to .eot converter. Windows only!
Till today there is no user-friendly offline webfont converter or generator available covering all webfont formats.