The general definition of peripherals in relation to computers is defined as any auxiliary device that connects to and works with the computer in some way. Peripherals can come in many varieties, and each have a specific purpose. Some peripherals you may know include, but are not limited to: computer mouses, keyboards, image scanners (such as printers), tape drives, microphones, speakers, webcams, and digital cameras. Most people don't realize this, but wifi routers, modems, and even USB flash drives are also peripherals.

Computer mouses- one of the most important components when using a computer, without this, you would have to rely on the computer's built-in mousepad, if it even has one.
Keyboards - Also one of the most important components of a computer, as it allows the user to input commands at the simple click of a "key".
Image scanners - An optional component, but essential if the user wants to use a computer to print out pictures or pages they find on the internet.
Tape drives- Although another optional component, a tape drive is able to read and write data on a magnetic tape. Armed with long stability, accessibility to offline data storage, and its low cost, tape drives are a great storage device.
Microphones/Speakers- Optional components, but they're useful for recording audio, can also be used in conferencing and podcasting.
Webcams- Optional component, can be used for a variety of things: conferencing, podcasting, streaming, and videochatting.
Digital Cameras-An additional component that can be used to capture and store sound, video, and images. Images can be uploaded to a printer or computer immediately.
Wifi Routers- Mandatory component for a user to use online features. Without it, a user can only run commands and use features that are available offline.
Modems - Also a mandatory component for online use that works in sync with wifi routers. They convert analog signals into digital signals, allowing you to connect to the Internet over a telephone or cable line.
USB Flash Drives- Handy additional component used to store data on a small stick.