Search engines understand text, but using text in an HTML webpage typically means using fonts available on the end user’s computer. That doesn’t give designers a lot of choice. There are now many techniques available to supply a font the browser will download and use, greatly expanding the design possibilities. The text remains live so search engines can fine and understand it and edits are much easier.
CSS Image Replacement
One approach to using non-standard fonts on your website is to use images. Images alone would not be very search-engine friendly though, so using CSS to replace the HTML text with images gives you the best of both worlds — text for search engines, and rich, appealing images for users. This may be the only option if the font license does not allow web embedding.