To link a file to an e-mail message so that they travel together to their destination. File attachments are a very common way of sending a file to someone. See e-mail attachment and how to transfer a file over the Internet.
"attach a file." YourDictionary, n.d. Web. 15 May 2018. <http://www.yourdictionary.com/attach-a-file>.
attach a file. (n.d.). Retrieved May 15th, 2018, from http://www.yourdictionary.com/attach-a-file