Documentation

iText in Action
The first place to look for information about iText is the iText book:
iText in Action,
the first and only book about iText.You can download two free chapters and/or buy the eBook from Manning Publications Co.
API documentation
With every new release, the API documentation is generated automatically, using the
javadoc tool that comes with the JDK. You can consult the API online
or download
iText-docs-2.1.7.tar.gz
with all the API documentation.
Tutorial and Code Samples
If you own the book, you have access to hundreds of small standalone examples
that are organized per chapter at 1T3XT.info
(note that you have to answer a magic question in order to see the examples).If you don't own the book, you could turn to the free online tutorial (iText by Example) or try the examples presented in the iText Wiki. Some more specialized examples can be found at articles @ itext.ugent.be.
Mailing-list
iText has a very active mailing-list. If you don't want to
register
rightaway, you can browse through the mailing-list archives
before sending your question to itext-questions@lists.sourceforge.net.Of course you should always consult the FAQ before you contact us.
If you do send a question to the list, try describing your problem as concrete as possible. We can't answer questions such as "Why doesn't iText work on my computer". Please keep in mind that it is really difficult for us to solve problems or track down bugs that we can't reproduce. If possible, send us a small standalone source code example, demonstrating the problem. Make sure we will be able to compile and execute it on our own virtual machine (we probably don't have the same database systems, external libraries, application servers,... you are using). Also send us the resulting PDF on your machine, so that we can compare it with the PDF that is generated by us, using your code.
Third Party Presentations
If you have written a presentation, a tutorial or some code samples you want
to share, please let me know and I'll add them here.There's an article on AdobePress about iText written by Jeff Friesen; it's titled Tools of the Trade, Part 1: Creating PDF documents with iText. You can also read the step by step guide Generate PDF files from Java applications dynamically by Amit Tuli (IBM). If you want to start with a very simple example, Christoph Bartneck has written you some pages on the step-by-step installation for Windows and Mac. There is also a page on Creating PDF-files.
If you need more and if you are used to a Web Application environment, Mark Stark has made a powerpoint presentation and a war file, introducing the generation of PDFs, filling/reading Acrobat forms and deploying iText in a web application.
Another interesting presentation is the powerpoint Sean Sullivan made for the Portland Java Users Group in Portland Oregon USA. The topic was iText and PDF. You can download his PowerPoint slides here or you can read the article he wrote for O'Reilly's onJava.com: Dynamically Creating PDFs in a Web Application.
If you want to fill forms, have a look at this blog-entry by Vince Schuurman.
For an introduction in German, I can refer you to an article in JavaMagazin by Cord Jastram. In a few selected examples, it gives you an overview of some powerful features such as generating an encrypted document, using PageEvents, generating Graphics, etc...
Ilie Nae wrote a similar article in Romanian for NetReport: Crearea de documente PDF in JAVA
If you understand Portuguese and you are using iText in the context of a Web Application, you can read the article Como fazer um servlet gerador de relatorios PDF by Pedro Burglin at Cafeh.com.br.
There are some specialized examples around too: The Serverside has an article on Inserting text to existing PDF file. There are examples available on making charts with JFreeChart and exporting them to PDF. If you want to use iText in a ColdFusion application, just read blog example first.