In its most basic form, a computer system is a programmable electronic device that can accept input; store data; and retrieve, process and output information.

• A computer is a device that is capable of receiving information (input), performing operations with that information (processing), and producing a result (output)
• A computer system is a computer that comes with software, hardware, and other peripherals that allow it to perform a certain task
• There are many types of computer systems, the most common being desktops, and mobile devices including laptops, and servers

• A desktop computer system is a personal computer system designed for use in a set location
• This is primarily due to its size and power requirements
• Unlike a mobile computing device such as a tablet, phone, or laptop, a desktop computer relies on a non-removable power supply plugged into the wall
• A desktop computer generally includes the system case with the computer's components, as well as common peripherals such as a keyboard, mouse, and monitor

• A mobile computer system is a computer system that is not constrained to one location
• Its size and use of a portable battery allow for the computer system to be moved freely
• Mobile computer systems often rely on alternate forms of input as they generally don't rely on external peripheral devices
  • Modern-day mobile phones, tablets, and even some laptops rely on touchscreen capabilities to accept input
  • This eliminates the need for a mouse and keyboard as a virtual keyboard is used instead
  • Laptop computer systems come with built-in mouse devices, known as a trackpad or touchpad, as well as a built-in keyboard
     

• A server is a computer system specifically designed to run services
• They work by accepting requests from the client (a user) and returning a response (such as a web page)
• The benefit of running a service on a dedicated computer such as a server is security
• Many types of servers exist, such as:
   
  • Mail servers = these store and move mail across the Internet
  • Web servers = These servers are responsible for loading web pages and other resources from a disk and serving it to the client (a user's web browser) over HTTP (hypertext transfer protocol)
  • FTP servers = allow for moving files securely between computers