what is raid code example

Example 1: what is ram

Random Access Memory, also know as just memory, is where files that need to be quickly accessed are stored. 
Ram has low storage, but high speeds, opposite to Storage, such as SSD's and HDD's.

Example 2: what is os

An Operating system (OS) is a software which acts as an interface between the end user and computer hardware. Every computer must have at least one OS to run other programs. An application like Chrome, MS Word, Games, etc needs some environment in which it will run and perform its task. The OS helps you to communicate with the computer without knowing how to speak the computer's language. It is not possible for the user to use any computer or mobile device without having an operating system.