AttachmentAn email attachment is a computer file sent along with an email message. One or more files can be attached to any email message, and be sent along with it to the recipient. This is typically used as a simple method to share documents and images. AnnexureAn annexure is an addition to something, often to a document. When used generally to simply mean something added, annexure is interchangeable with annex. Annexure is more commonly used in the U. K. and India, where it often specifically refers to an addition to an official document. PDFThe full form of PDF is Portable Document Format. They are typically used to distribute read-only documents that preserve the layout of a page. It was developed in the early 1990s by Adobe Systems. PDF provides an easy and secure approach for data transmission and sharing through emails and other sources.