@font-face is a specification in CSS 2 and 3 that allows the server to specify a nonstandard font for display in the browser, providing a file containing the font if the client does not have it installed locally.
Though font-face has been technically usable in some browsers for many years, licensing issues with font foundries and the reluctance of the browser industry to adopt one standard font access format have made the specification extremely underused.
Into the vacuum left by the lack of @font-face support grew various ways to replace the unsatisfying Microsoft Core Fonts. For some time, designers simply replaced parts of their sites with images in order to give the appearance of using more unique fonts. Unfortunately, this reduced the ability of the pages to be fully semantic and weakened searchability. In response, two effective font-replacement technologies: sIFR and Cufon, based on flash and vector graphics respectively, emerged to offer a compromise between @font-face and image replacement.
Recently, progress has been made as the lead versions of Firefox, Opera and Safari all support the embedding of TrueType and OpenType fonts from server locations. Again, however, such applications risk running afoul of the fonts' licensing agreements, so usage has been limited to open source and public domain fonts.
The Web Open Font Format (WOFF) suggests a new progress in this area. It compresses the source font files in such a way that makes directly stealing them out of servers impractical, allaying the fears of type foundries that their creations would be stolen en masse were @font-face to become widely used. WOFF has been backed by Mozilla, Microsoft, and the larger type foundries, so it currently appears to finally offer a realization of the @font-face property.