Level 0: The Foundation

Dark industrial floor with glowing red neon grid seams running in precise lines: the invisible infrastructure beneath every digital system. — Every cloud service, every API, every AI model runs on physical hardware connected by physical networks. Level 0 is where that reality becomes visible.

Level 0 of 4

The foundation beneath everything

Before containers, before APIs, before language models, there is hardware. Processors, memory, storage, and cables. Software is instructions. Instructions need a machine to run on. Networks carry results from one machine to another.

Level 0 covers exactly that physical and network reality. Two articles. No prior knowledge assumed. By the end, you have the mental model that makes every later concept make sense.

What you know after Level 0

Hardware

CPU RAM Storage GPU Four components that define every computing device, from phone to data centre server

Operating System

Windows / macOS / Linux iOS / Android The software layer that manages hardware and lets applications run on top

Networking

IP addresses DNS TCP/IP HTTP Protocols that define how data travels from one machine to another, globally

Data encoding

Bits and bytes Packets Binary How everything, text, images, video, becomes numbers that machines can transmit and store

Learning path

Start here Hardware basics CPU, RAM, storage, GPU. What each does and why the four work together.

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Layer 2 Operating systems The software that sits between hardware and applications. Why it exists and what it manages.

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Layer 3 Network protocols IP, DNS, TCP. The agreed standards that let any machine talk to any other machine.

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Layer 4 Data transmission How data becomes packets, travels across fibre and radio, and reassembles at its destination.

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Ready Level 1 You now understand what runs software and how machines communicate. Level 1 starts where this ends.

Before and after

	Before Level 0	After Level 0
Hardware	“My laptop has 16GB” but no idea what that means	RAM holds running processes; storage holds files; 16GB RAM means 16 billion bytes of working memory
The internet	“Data goes through the internet somehow”	IP addresses identify machines; DNS translates names; TCP breaks data into packets and reassembles them
Cloud vs local	Both run software, unclear what differs	Cloud is hardware in a data centre; local is hardware on your desk; the OS and protocols are identical
AI hardware	“AI needs special computers”	GPUs run AI because they do parallel arithmetic; the same GPUs that render games train language models
Network delays	“It’s slow”	Latency is the physical time for packets to travel; distance and hops between servers are measurable
Crashes and failures	“It stopped working”	Hardware state, OS resource limits, and network failures are distinct, diagnosable categories

Articles in this level

What is a Computer?

The four components that define any computing device, from a phone to a server rack. Covers CPU, RAM, storage, and GPU in plain English. Explains why binary is the underlying language of all digital systems and why GPUs became the hardware of the AI era. Includes the layered architecture diagram from transistor to application.

You should read this if: You use software every day but could not explain what a CPU does or why a server is different from a laptop.

What is the Internet?

How data moves between machines across the globe. Covers IP addresses, DNS, TCP/IP, HTTP, and the physical infrastructure of cables and routers that make global communication possible. Explains what actually happens between the moment you press Enter and the moment a webpage appears.

You should read this if: You know the internet exists but have never thought about what IP addresses are, what DNS resolves, or why some requests are slower than others.

Why this matters in practice

Knowing the physical and network layer beneath software is not optional background knowledge. It shapes real decisions.

Scale decisions: When a product team asks “can this handle a million users?”, the answer depends on CPU cores, memory limits, network bandwidth, and database connections. You cannot answer that question without understanding what those terms mean at a hardware level.

Latency decisions: “Why is the API slow for users in Australia?” is a geography and network question. Understanding that packets travel at the speed of light across physical cables makes that question answerable. Putting a CDN edge node closer to those users reduces the physical distance data travels.

AI infrastructure decisions: Every language model runs on GPU clusters. Every inference request is a network call. The cost of running an AI product is, at its core, a compute and bandwidth cost. Level 0 gives you the vocabulary to read a cloud bill and understand what you are paying for.

Debugging conversations: When an engineer tells you “the pod ran out of memory” or “the DNS change hasn’t propagated yet”, you will follow the conversation instead of nodding along. That matters in sprint reviews, incident retrospectives, and vendor negotiations.

What comes next

You are here

Level 0: The Foundation Hardware, operating systems, networks, data transmission

Up next

Level 1: How Code Works Terminals, file systems, instructions, and how code becomes running software

Start Level 1: How Code Works →

The terminal is the direct interface to everything you learned in Level 0. Level 1 shows you how developers use it and what code actually is.