FPDF is a PHP class which allows to generate PDF files with pure PHP, that is to say without using the PDFlib library. F from FPDF stands for Free: you may use it for any kind of usage and modify it to suit your needs.
FPDF has other advantages: high level functions. Here is a list of its main features:
Choice of measure unit, page format and margins
Page header and footer management
Automatic page break
Automatic line break and text justification
Image support (JPEG, PNG and GIF)
Colors
Links
TrueType, Type1 and encoding support
Page compression
FPDF requires no extension (except zlib to activate compression and GD for GIF support) and works with PHP4 and PHP5.