Cloud Computing

What is Cloud Computing?

Cloud Computing is the delivery of computing services—including servers, storage, databases, networking, and software—over the Internet ('the cloud'). Instead of buying and maintaining physical hard drives or servers, you rent them from a cloud provider (like Amazon AWS, Microsoft Azure, or Google Cloud) and pay only for what you use.

1. Cloud Deployment Models

A. Public Cloud

• Owned and operated by a third-party cloud service provider. You share the same hardware, storage, and network devices with other organizations ('cloud tenants').
• Pros: Low cost, no maintenance, highly scalable.
• Cons: Less control over security.

B. Private Cloud

• Cloud computing resources used exclusively by a single business or organization. The physical servers might be located on-site in the company's own data center.
• Pros: Maximum security, complete control.
• Cons: Very expensive, requires your own IT staff to maintain.

C. Hybrid Cloud

• A combination of Public and Private clouds. Data and applications can move between them.
• Example: A bank uses a Private Cloud for highly sensitive customer data, but uses a Public Cloud to run their public website.

2. Cloud Service Models (IaaS, PaaS, SaaS)

A. IaaS (Infrastructure as a Service)

• What it is: You rent the bare-bones IT infrastructure—servers, virtual machines (VMs), storage, and networks. It's like renting an empty plot of land; you have to build the house yourself.
• Who uses it: IT Administrators.
• Examples: Amazon EC2, Microsoft Azure VMs.

B. PaaS (Platform as a Service)

• What it is: The provider gives you the infrastructure PLUS the operating system and development tools. It's designed to make it easy for developers to quickly create web or mobile apps without worrying about setting up servers.
• Who uses it: Software Developers.
• Examples: Google App Engine, Heroku.

C. SaaS (Software as a Service)

• What it is: A complete, fully-finished software application delivered over the internet. You don't manage anything except your own user account.
• Who uses it: End Users (Everyone).
• Examples: Gmail, Microsoft Office 365, Netflix, Dropbox.