A PDF Library is a collection of software tools and resources designed to create, manipulate, and manage PDF (Portable Document Format) files. These libraries provide developers with the ability to generate PDFs programmatically, extract text and images, and modify existing documents. They are commonly used in applications that require document generation, such as invoicing systems and report generators. Many programming languages, including Java, Python, and C#, have their own PDF libraries, such as iText, PyPDF2, and PDFsharp. These libraries simplify the process of working with PDFs, allowing users to focus on their application's functionality rather than the complexities of the PDF format itself.