An "e" placed before a word or phrase stands for "electronic." For example, an e-book is an electronic version of a book. Commonly used in the media to describe something that has to do with being online, e- has prefaced nearly everything in the real world that can be made electronic, including: e-campaign, e-life, e-broker, and so forth. For a detailed discussion on when to use the hyphen and when not to use it, see the e-mail definition.
NetLingo Classification: Online Jargon