iText is a popular software library used for creating and manipulating PDF documents in various programming languages, including Java and C#. It allows developers to generate dynamic PDFs, fill forms, and add digital signatures, making it a valuable tool for applications that require document generation and management. The library is open-source and offers both a free version and a commercial version with additional features. iText is widely used in industries such as finance, healthcare, and legal services, where precise document handling and compliance with standards are essential for business operations.