FPDF

FPDF is a PHP class which allows to generate PDF files with straight PHP, that is to say without using the PDFlib library. The advantage is that the latter requires a fee for a commercial usage. F from FPDF stands for Free: you may use it for any kind of usage and modify it to 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 and PNG)
Colors
Links
TrueType, Type1 and encoding support
Page compression