Starting with PDF 1.3 (Adobe Acrobat 4.0), PDF files can contain file attachments — arbitrary files that a reader can extract, just like attachments to an e-mail message. The attachfile package brings this functionality to pdfLaTeX and provides some additional features not available in Acrobat, such as the ability to use arbitrary LaTeX code for the file icon — including things like \includegraphics, tabular, and mathematics. Settings can be made either globally or on a per-attachment basis. Attachfile makes it easy to attach files and customize their appearance in the enclosing document. The package supports the Created, Modified, and Size keys in the EmbeddedFile’s Params dictionary.