This document discusses laptops, notebooks, PDAs, and instant messaging. It describes laptops and notebooks as mobile versions of personal computers that provide desktop capabilities in a portable form. PDAs are described as small handheld computers that function as personal information managers. Instant messaging allows real-time text exchanges between users who are online simultaneously. The document outlines various business uses and advantages of these technologies, such as easy customer interaction and maintenance of close relationships, though also notes some disadvantages like health issues and limited battery life.