Different deployment models of cloud computing include:

a) Public Cloud – Standard cloud computing model.

b) Community Cloud – Infrastructure shared between several organizations.

c) Hybrid Cloud – Composed of multiple clouds bound together to provide services.

d) Private Cloud – Clouds intended for a single organization only.
Internet-based email accounts have been utilized since the emergence and popularization of the internet. Internet-based email accounts are another cloud service that is offered. One of the pioneers includes Hotmail, Yahoo and MSN. This way Internet-based email can be regarded as one of the first cloud services because you have a fully functioning email account hosted on an external server.
A cloud computing service can be thought of as consisting of three pyramid layers. These layers are:

a) Cloud Infrastructure

b) Cloud Platform

c) Cloud Application
A cloud is a blend of hardware, storage, networks, interfaces and services that aid in delivering computing as a service. A cloud consists of three users:end-user, cloud service provider and business management user.
The basic four characteristics of cloud computing are:

a) Scalability and elasticity – Increase or decrease services on demand

b) Self-service provisioning – Help yourself in major problematic scenarios without waiting for the response of your provider

c) Pay-per-usage billing model – Pay for what you use

d) Standardized interfaces – Interfaces applicable to all major models