What is Cloud Computing?

Cloud computing has transformed how businesses and developers build, deploy, and scale applications. In this lesson, we'll explore what cloud computing really means, why it matters, and how AWS became the world's leading cloud platform.

What You'll Learn

By the end of this lesson, you'll understand the fundamental concepts of cloud computing, the different service models (IaaS, PaaS, SaaS), and why organizations are moving to the cloud.

The Simple Definition

Cloud computing is the delivery of computing services over the internet. Instead of buying, owning, and maintaining physical servers and data centers, you can rent access to computing resources from a cloud provider like Amazon Web Services (AWS).

These resources include:

• Compute power - Virtual servers to run your applications
• Storage - Space to store your data
• Databases - Managed database services
• Networking - Virtual networks and content delivery
• Analytics - Tools to process and analyze data
• Machine Learning - AI and ML services

Think of it like electricity: you don't need to own a power plant to power your home. You simply plug in and pay for what you use.

Before the Cloud: The Old Way

Before cloud computing, if you wanted to run an application, you needed to:

1. Buy physical servers - Expensive hardware that might cost thousands of dollars
2. Set up a data center - Rent space, install cooling, ensure physical security
3. Hire IT staff - People to maintain and manage the infrastructure
4. Plan for capacity - Guess how much computing power you'd need years in advance
5. Wait weeks or months - For hardware to be ordered, shipped, and configured

This approach had major problems:

Problem	Impact
High upfront costs	Needed significant capital investment before launching
Capacity planning	Over-provision (waste money) or under-provision (poor performance)
Slow to scale	Adding capacity took weeks or months
Maintenance burden	Constant patching, updates, and hardware replacement
Limited flexibility	Locked into hardware decisions for years

The Cloud Revolution

Cloud computing flipped this model on its head:

• No upfront costs - Pay only for what you use
• Instant provisioning - Launch servers in seconds, not weeks
• Elastic scaling - Automatically add or remove capacity based on demand
• Global reach - Deploy applications worldwide with a few clicks
• Managed services - Let the cloud provider handle maintenance

A Real Example

Imagine you're launching a new e-commerce website:

Old Way: You estimate you'll need 10 servers. You buy them, set them up over 2 months, and launch. On Black Friday, traffic spikes 10x - your site crashes because you don't have enough capacity. The rest of the year, those 10 servers sit mostly idle, wasting money.

Cloud Way: You launch with 2 virtual servers. Traffic spikes on Black Friday - AWS automatically scales to 50 servers to handle the load. After the rush, it scales back down to 2. You only pay for what you actually use.

Cloud Service Models

Cloud computing services are typically categorized into three models:

Infrastructure as a Service (IaaS)

IaaS provides the fundamental building blocks: virtual servers, storage, and networking. You manage the operating system, applications, and data.

AWS Examples: EC2 (virtual servers), EBS (storage), VPC (networking)

You manage: Operating system, middleware, applications, data Provider manages: Hardware, networking, data centers

Best for: When you need maximum control and flexibility

Platform as a Service (PaaS)

PaaS provides a platform for building and deploying applications without managing infrastructure. You focus on your code; the provider handles everything else.

AWS Examples: Elastic Beanstalk, Lambda, App Runner

You manage: Application code and data Provider manages: Operating system, runtime, servers, storage

Best for: Developers who want to focus on code, not infrastructure

Software as a Service (SaaS)

SaaS delivers complete applications over the internet. You simply use the software; the provider handles everything.

Examples: Gmail, Salesforce, Slack, Netflix

You manage: Your data and user settings Provider manages: Everything else

Best for: Ready-to-use applications

Visual Comparison

                    On-Premises    IaaS        PaaS        SaaS
                    -----------    ----        ----        ----
Applications        You            You         You         Provider
Data                You            You         You         Provider
Runtime             You            You         Provider    Provider
Middleware          You            You         Provider    Provider
Operating System    You            You         Provider    Provider
Virtualization      You            Provider    Provider    Provider
Servers             You            Provider    Provider    Provider
Storage             You            Provider    Provider    Provider
Networking          You            Provider    Provider    Provider

Why AWS?

Amazon Web Services (AWS) launched in 2006 and pioneered the modern cloud computing industry. Today, it's the world's most comprehensive and widely adopted cloud platform.

AWS by the Numbers

• 200+ fully featured services
• 32 geographic regions worldwide
• Millions of active customers
• #1 market share in cloud computing

Why Organizations Choose AWS

1. Breadth of services - Whatever you need, AWS probably has it
2. Global infrastructure - Deploy close to your users anywhere in the world
3. Security - Built with security at its core, trusted by governments and enterprises
4. Innovation - Constantly releasing new services and features
5. Community - Vast ecosystem of partners, documentation, and support

Cloud Deployment Models

How you deploy your cloud infrastructure is another important decision:

Public Cloud

Resources are owned and operated by a cloud provider and shared among multiple customers. You access them over the internet.

Pros: No upfront investment, instant scalability, global reach Cons: Less control, shared infrastructure, potential compliance concerns

Private Cloud

Cloud infrastructure dedicated to a single organization. Can be hosted on-premises or by a third party.

Pros: Maximum control, enhanced security, compliance friendly Cons: Higher cost, requires expertise to manage

Hybrid Cloud

Combines public and private clouds, allowing data and applications to move between them.

Pros: Flexibility, keep sensitive data on-premises, burst to cloud for peaks Cons: Complexity, requires careful architecture

AWS supports all three models, but this course focuses primarily on the public cloud.

Key Takeaways

• Cloud computing delivers computing resources over the internet on a pay-as-you-go basis
• Traditional infrastructure required high upfront costs, long provisioning times, and capacity guessing
• The cloud offers instant provisioning, elastic scaling, and no upfront costs
• Service models (IaaS, PaaS, SaaS) offer different levels of control vs. convenience
• AWS is the leading cloud platform with 200+ services and global infrastructure
• Deployment models (public, private, hybrid) offer different tradeoffs

What's Next

Now that you understand what cloud computing is and why it matters, let's get hands-on. In the next lesson, we'll create your AWS account and set up secure access using Identity and Access Management (IAM).