mPDF is a PHP class which generates PDF files from UTF-8 encoded HTML. It is based on FPDF and HTML2FPDF with a number of enhancements.
The original author, Ian Back, wrote mPDF to output PDF files 'on-the-fly' from his website, handling different languages. It is slower than the original scripts e.g. HTML2FPDF and produces larger files when using Unicode fonts, but support for CSS styles etc. and has been much enhanced – see the features.