 Historically this was an electronic mail, but it may also include instant messages, audio messages (such as those in VoIP), text messages, facsimile messages, or other user collaboration protocol data structures.Beginning about 2005 electronic messages began to include social media that included user-generated content such as blogs, discussion forums, posts, chats, tweets, podcasting, pins, digital images, video and audio files.Several implementation variations exist, altering when, what, and how information is retained.