Introduction To Unity Particle System

Notes:

Particle System - Introduction

What is a particle?
Particle is a small individual 2D sprite (or 2D image) or 3D mesh (or a 3D model); which undergoes various changes during its life time.
Ex: In a Rain Effect each water drop can be considered as a particle.

What is a particle system?
Particle system emits a collection of particles within a specified shape. It is a system of multiple modules working together to create some particle effect.
Ex: Rain Effect, Smoke effect, Fire effect, Blast effect, Snowfall Effect, Tornado effect etc.

Creating a particle system in Unity:
Game Object Menu - Particle System