I.M. (usually spelled 'IM' without the periods) is instant messaging, a form of modern online chatting. IM is somewhat like texting, somewhat like email, and very much like sending notes in a classroom. IM uses specialized no-cost software that you install on your computer. That IM software in turn connects you to potentially thousands of other IM users through the Internet. You locate existing friends and make new friends by searching for their IM nicknames. Once the software and your friends list is in place, you can send instantaneous short messages to each other, with the option of including file attachments and links. While the recipient sees your message instantly, they can choose to reply at their leisure.