Before cloud computing, if you wanted to launch a website or run a business application, you had to buy and manage your own physical servers. This meant finding space for them, paying for electricity, and hiring people to maintain them. It was expensive and slow.

Cloud computing changes all that. Instead of owning your own computing infrastructure, you can rent it from a cloud provider like Amazon Web Services (AWS). Think of it like electricity. You don't build your own power plant; you just plug into the grid and pay for what you use. The cloud is a global grid of data centres that you can access over the internet.

This pay-as-you-go approach gives businesses incredible flexibility. They can scale up their resources during busy periods and scale down when things are quiet, only paying for what they actually use. This eliminates the need for large upfront investments in hardware and allows teams to move much faster.

Amazon Web Services (AWS) is the world's most popular cloud platform. It started in 2006, offering just a few basic services. Today, it provides hundreds of services for nearly any task you can imagine, from running simple websites to powering complex machine learning models.

These services fall into broad categories like compute, storage, databases, networking, and analytics. Instead of being one single product, AWS is a collection of building blocks that you can assemble in countless ways to build and run your applications.

To deliver services reliably and quickly around the world, AWS has built a massive global infrastructure. This physical network of data centres is organised into two key concepts: Regions and Availability Zones.

Regions allow you to place your resources and data in specific geographic areas. This is useful for reducing latency for your users and complying with data residency laws.

Within each Region, there are multiple, isolated locations known as Availability Zones.

Think of a Region as a major city, and Availability Zones (AZs) as separate neighbourhoods within that city. Each AZ is designed to be isolated from failures in other AZs. If one data centre has a power outage, the others in the same region keep running.

This structure is the key to building fault-tolerant and highly available applications. By distributing your application's resources across multiple AZs, you can ensure it stays online even if one entire data centre goes down. This is a fundamental concept for troubleshooting and designing resilient systems on AWS.

While AWS offers a huge portfolio of services, a few are considered the foundational pillars of the platform. Understanding these is the first step to working with AWS.

These services work together. You might use IAM to control who can launch an EC2 virtual server, which runs inside a VPC network and stores its data in S3. Grasping how these core pieces fit together is essential for building and troubleshooting any application on AWS.

Now that you've got the basics down, you understand the fundamental concepts of cloud computing and how AWS structures its global platform for reliability and scale.