**1. History of Online and Offline:**
– The term ‘on line’ was used in the 19th century in the railroad and telegraph industries.
– Railroads used signals like ‘Train on line’ and ‘Line clear’ via telegraph lines.
– Computing terms ‘on-line’ and ‘off-line’ have been used since at least 1950.
– Automatic transcription of data for on-line operation was mentioned in a 1950 book.
– Comparison to teleprinter operating requirements was provided.
**2. Examples of Online and Offline Use:**
– Offline e-mail can be managed with mail user agents like Microsoft Outlook.
– Digital audio technology uses online and offline states for synchronization.
– Web browsers can be instructed to be in online or offline states for browsing.
– Offline browsing allows users to access previously downloaded pages.
– Offline information stores like WiderNets eGranary Digital Library provide access in areas with limited connectivity.
**3. Offline Communication and Media:**
– Offline e-mail can be managed with mail user agents like Microsoft Outlook.
– Digital audio devices sync online to a master clock for playback.
– Offline browsing allows access to locally stored web pages.
– Offline storage is data storage without connection until deliberate connection.
– Powered down online systems are considered offline.
**4. Importance of Offline Capabilities:**
– Offline mode in web browsers is useful in areas with no or limited Internet connectivity.
– Offline storage ensures data security and prevents unauthorized access.
– Backup and recovery processes often involve offline storage.
– Offline information stores like eGranary Digital Library provide offline access to educational resources.
– Offline storage is useful for critical data protection and disaster recovery planning.
**5. Generalizations and Implications of Online and Offline:**
– Online and offline distinctions have been generalized from computing and telecommunication into human interpersonal relationships.
– The distinction between online and offline is conventionally seen as the distinction between computer-mediated communication and face-to-face communication.
– Legal and regulatory pressures aim to reduce the distinction between online and offline.
– The distinction between online and offline is sometimes inverted, with online concepts defining and explaining offline activities.
– Some people draw no distinction between an online relationship, like cybersex, and an offline relationship, like being pen pals.
In computer technology and telecommunications, online indicates a state of connectivity and offline indicates a disconnected state. In modern terminology, this usually refers to an Internet connection, but (especially when expressed "on line" or "on the line") could refer to any piece of equipment or functional unit that is connected to a larger system. Being online means that the equipment or subsystem is connected, or that it is ready for use.
"Online" has come to describe activities performed on and data available on the Internet, for example: "online identity", "online predator", "online gambling", "online game", "online shopping", "online banking", and "online learning". Similar meaning is also given by the prefixes "cyber" and "e", as in the words "cyberspace", "cybercrime", "email", and "ecommerce". In contrast, "offline" can refer to either computing activities performed while disconnected from the Internet, or alternatives to Internet activities (such as shopping in brick-and-mortar stores). The term "offline" is sometimes used interchangeably with the acronym "IRL", meaning "in real life".