What is a Computer Software ?

Computer software is a general term used to describe a collection of computer programs, procedures and documentation that perform some task on a computer system. The term includes application software such as word processors which perform productive tasks for users, system software such as operating systems, which interface with hardware to provide the necessary services for application software, and middleware which controls and co-ordinates distributed systems.

source:wikipedia

Output

Image, Video output devices
Printer - a peripheral device that produces a hard (usually paper) copy of a document.
Monitor - device that displays a video signal, similar to a television, to provide the user with information and an interface with which to interact.
Audio output devices
Speakers- a device that converts analog audio signals into the equivalent air vibrations in order to make audible sound.
Headset - a device similar in functionality to computer speakers used mainly to not disturb others nearby.

source:wikipedia

Input

Text input devices
Keyboard - a device, to input text and characters by depressing buttons (referred to as keys), similar to a typewriter. The most common English-language key layout is the QWERTY layout.
Pointing devices
Mouse - a pointing device that detects two dimensional motion relative to its supporting surface.
Trackball - a pointing device consisting of an exposed portruding ball housed in a socket that detects rotation about two axes.
Gaming devices
Joystick - a general control device that consists of a handheld stick that pivots around one end, to detect angles in two or three dimensions.
Gamepad- a general game controller held in the hand that relies on the digits (especially thumbs) to provide input.
Game controller - a specific type of controller specialized for certain gaming purposes.
Image, Video input devices
Image scanner - a device that provides input by analyzing images, printed text, handwriting, or an object.
Webcam - a low resolution video camera used to provide visual input that can be easily transferred over the internet.
Audio input devices
Microphone - an acoustic sensor that provides input by converting sound into an electrical signal

source:wikipedia

Other peripherals

In addition, hardware can include external components of a computer system. The following are either standard or very common.

Wheel mouse
Includes various input and output devices, usually external to the computer system

source:wikipedia