A personal computer (PC) is any general-purpose computer  whose size, capabilities, and original sales price make it useful for  individuals, and which is intended to be operated directly by an end-user with no intervening computer operator. In contrast, the batch processing or time-sharing models allowed large expensive mainframe  systems to be used by many people, usually at the same time. Large data  processing systems require a full-time staff to operate efficiently.
 Software applications for personal computers include, but are not limited to, word processing, spreadsheets, databases, Web browsers and e-mail clients, digital media playback, games,  and myriad personal productivity and special-purpose software  applications. Modern personal computers often have connections to the Internet, allowing access to the World Wide Web and a wide range of other resources. Personal computers may be connected to a local area network (LAN), either by a cable or a wireless connection. A personal computer may be a desktop computer or a laptop, tablet PC, or a handheld PC.
 While early PC owners usually had to write their own programs to do  anything useful with the machines, today's users have access to a wide  range of commercial software and free software, which is provided in ready-to-run or ready-to-compile form. Since the 1980s, Microsoft and Intel have dominated much of the personal computer market, first with MS-DOS and then with the Wintel platform. Alternatives to Windows include Apple's Mac OS X and the open-source Linux OSes. AMD  is the major alternative to Intel. Applications and games for PCs are  typically developed and distributed independently from the hardware or  OS manufacturers, whereas software for many mobile phones and other  portable systems is approved and distributed through a centralized  online store.[1][2]
 In July & August 2011, marketing businesses and journalists  started to talk about the 'Post-PC Era', an era where the desktop form  factor was being replace with more portable computing such as netbooks,  and Tablet PC's.