The Three Pillars: Compute, Storage, Networking

The cloud, simplified

Cloud providers like AWS offer hundreds of services, which is genuinely overwhelming at first. Here's the secret that makes it all manageable: almost every cloud service is a flavour of just three fundamentals — compute, storage, and networking. Master these three pillars, and the entire cloud suddenly has structure. Every fancy service is really one of these three, specialised for a particular job.

Pillar 1: Compute (the "doing")

Compute is processing power — the part that actually runs your code and does work. Whenever you need a program to execute, a website to serve requests, or data to be processed, that's compute. It's the cloud's equivalent of a CPU doing the thinking.

The classic form of compute is a virtual server (also called a virtual machine or "instance") — essentially a computer in the cloud that you control, install software on, and run your app on. On AWS this is the famous EC2 service. You pick how powerful you want it (more CPU and memory cost more), launch it in minutes, and it's yours to use. There are also more modern compute styles — like "serverless", where you just run a function without managing any server at all — but they're all variations on the same idea: somewhere to run your code.

Pillar 2: Storage (the "keeping")

Storage is where your data lives — files, images, videos, backups, databases. Compute does the work, but the data has to be kept somewhere persistent, and that's storage. The cloud offers different storage types for different needs, which is an important practical distinction:

• Object storage — for files of any kind (images, videos, documents, backups). Massively scalable and cheap. On AWS this is S3, one of the most-used cloud services in the world.
• Block storage — acts like a hard drive attached to a virtual server, for the operating system and apps. On AWS this is EBS.
• Database storage — structured data in databases (covered in its own chapter, since databases are so central).

The key practical insight is matching the storage type to the job: use object storage (S3) for files and media, block storage (EBS) for a server's working drive, and a database for structured records. Choosing the right one is a real cloud skill, and it affects both cost and performance.

Pillar 3: Networking (the "connecting")

Networking is what connects everything together and to the outside world — letting your servers talk to each other, to your database, and to your users over the internet. It's the plumbing that ties compute and storage into a working system, and it's where a lot of cloud security lives.

Key networking ideas you'll meet: a VPC (Virtual Private Cloud) is your own private, isolated network in the cloud where your resources live securely. Load balancers spread incoming traffic across multiple servers so no single one is overwhelmed (essential for handling lots of users). DNS connects human-friendly addresses (like yoursite.com) to your servers. And security controls like firewalls decide what traffic is allowed in and out. Networking can feel abstract at first, but it's how a collection of servers and storage becomes a real, secure, accessible application.

How the pillars work together

Let's see the three pillars combine into something real. Imagine a simple photo-sharing app. Here's how each pillar plays its part:

  A user uploads a photo to the app:

  NETWORKING → the request travels over the internet, through a
               load balancer, into your private cloud network (VPC)
  COMPUTE    → a virtual server (EC2) receives it and runs your
               code to process the upload
  STORAGE    → the photo file is saved to object storage (S3),
               and its details recorded in a database

  When another user views it, the reverse happens —
  networking routes the request, compute serves the page,
  storage provides the photo.

Every cloud application, no matter how complex, is fundamentally this dance of compute (running code), storage (keeping data), and networking (connecting it all). Even a huge system like Netflix is just these three pillars at enormous scale, with many specialised services layered on top.

Why this framework matters

When you next see AWS's intimidating list of 200+ services, you'll have a map: is this service about compute, storage, or networking? Almost every one slots into a pillar (or combines them). A database service? Specialised storage. A content delivery network? Specialised networking. A container service? Specialised compute. This mental model turns chaos into clarity, and it's the foundation for everything else in this course. Next, we'll get concrete and meet the specific AWS services you'll actually use, starting with the two most famous: EC2 and S3.