A PDF Reader is a software application that allows users to open, view, and interact with PDF (Portable Document Format) files. These files are commonly used for sharing documents because they maintain the original formatting, making them look the same on any device. With a PDF reader, you can read e-books, manuals, and reports easily, without worrying about changes in layout. Many PDF readers also offer additional features, such as highlighting text, adding comments, and filling out forms. Some popular PDF readers include Adobe Acrobat Reader, Foxit Reader, and SumatraPDF. These tools make it simple to manage and work with PDF documents efficiently.