One idea,
one analogy.
The concepts engineers reach for, each in plain English with a single analogy and no jargon. Read one in a minute, then follow the link to the full, technical version when you want the depth.
Networking & the web.
11 explainersHTTPS comic
A locked box you and the website both hold a key to, agreed out in the open.
DNS comic
The internet's phone book: it turns a name you can remember into the number a computer needs.
TCP vs UDP comic
Registered mail that is tracked and re-sent, versus postcards you fire off and hope arrive.
Load balancers comic
The host at a busy restaurant, seating each new guest at the emptiest table.
CDNs comic
A local branch of the warehouse, so your delivery comes from across town, not across the world.
What happens when you type a URL comic
Press Enter and a quick relay race begins: find the address, open a line, lock it, ask for the page, draw it.
JWTs (JSON Web Tokens) comic
A festival wristband: checked at a glance, with no call back to the box office.
WebSockets comic
One phone call that never hangs up, so the server can finally speak first.
REST vs GraphQL comic
A fixed menu where each dish is a separate order, versus telling the kitchen exactly what you want on one plate.
gRPC comic
Two services that studied the same rulebook once, then speak in dense shorthand forever after.
Reverse proxy comic
A receptionist who takes every visitor at the front desk and quietly routes them to the right office in back.
Databases & storage.
11 explainersDatabase indexes comic
The index at the back of a book, instead of reading every page to find a word.
ACID transactions comic
A bank transfer that cannot half-happen: either the whole thing lands, or none of it does.
SQL vs NoSQL comic
Labelled filing cabinets with strict folders, versus a fast drawer you can toss anything into.
Caching comic
Keeping the milk on the counter instead of walking to the fridge every time.
Sharding comic
Splitting one giant phone book into A–M and N–Z so two people can search at once.
Bloom filters comic
A bouncer’s “definitely not on the list” memory: tiny, fast, and never wrongly says no.
Write-ahead log (WAL) comic
Jot the move in a notebook before you make it, so a crash can’t lose it.
Redis (in-memory store) comic
The sticky-note wall by your desk for the things you grab constantly.
Isolation levels comic
A dial deciding how much of everyone else’s half-finished typing your transaction gets to see.
Replication comic
Keeping copies of your data on several machines, so a failure or a far-away reader is no big deal.
B-tree vs LSM-tree comic
Filing each card neatly in place as it arrives, versus jotting everything in order and tidying up in batches later.
Distributed systems.
15 explainersThe CAP theorem comic
When the network splits, you can keep answering or keep everyone in sync, but not both.
Consensus (Raft) comic
A group agreeing on one version of the story, even when some members go quiet.
Eventual consistency comic
Gossip: tell one person, and given a little time, everyone hears the news.
Idempotency comic
Pressing the elevator button twice does not call two elevators.
Message queues comic
A to-do inbox between two services, so work is not dropped when one of them is busy.
Kafka & pub/sub comic
A newspaper: published once, and any number of subscribers read it at their own pace.
The circuit breaker comic
A fuse that trips so a failing service can’t drag the rest down with it.
Split-brain comic
The radio dies, both halves of the crew promote a captain, and both captains start giving orders.
Monolith vs microservices comic
One big shop where everyone works under one roof, versus a row of specialist stalls that each run themselves.
Consistent hashing comic
Seats around a circle, so a newcomer bumps one neighbour instead of reshuffling the room.
Exponential backoff comic
Retry the way you re-text a silent friend: once soon, then with longer and longer gaps.
Quorum comic
Nothing counts until most copies say yes — and any two majorities always share a witness.
Service discovery comic
Nobody memorises the taco truck’s corner — you check where it parked this morning.
Service mesh comic
Giving every service its own personal assistant that handles all the calls, so the app code can stay simple.
Distributed lock comic
A single key, held across machines, that lets only one of them touch a shared thing at a time.
How computers work.
12 explainersProcess vs thread comic
A process is a kitchen; threads are the cooks working inside it.
RAM vs disk comic
RAM is your desk; the disk is the filing cabinet across the room.
CPU cache comic
Keeping the tools you reach for most in your apron pocket, not on the far shelf.
Hash functions comic
A blender that turns anything into a fixed-size fingerprint.
Big-O notation comic
Not how fast something is today, but how the work grows as the line gets longer.
Recursion comic
Nesting dolls: solve a problem by doing the same smaller version of it, until one is tiny enough to answer outright.
Garbage collection comic
A tidy-up crew that clears away any object nobody is pointing at anymore, so you don’t free memory by hand.
Stack vs heap comic
A neat stack of trays you add and remove from the top, versus a big warehouse where you ask for space and must give it back.
The event loop comic
One waiter covers the whole restaurant by refusing to ever stand and watch food cook.
Race conditions comic
Two people grabbing the last cookie at once because each looked, saw it there, and reached.
Virtual memory comic
Giving every program its own private, tidy address space, while the OS quietly maps it onto the real, messy RAM.
Concurrency vs parallelism comic
Interleaving tasks so nothing stalls, versus literally doing two at once — a skill versus a head-count.
Security & glue.
11 explainersPublic-key crypto comic
A padlock anyone can snap shut, but only you hold the key to open.
What an API is comic
A restaurant menu: you order from a set list, and the kitchen handles the rest.
Containers (Docker) comic
Shipping your app with its whole kitchen, so it runs the same anywhere.
Rate limiting comic
A bouncer at the door letting people in at a steady pace, not all at once.
OAuth (“sign in with…”) comic
A valet key: you let an app do one specific thing without ever handing over your real password.
CORS comic
A bouncer who phones the other building first: “is this guest allowed to talk to you?” before a page calls another site.
Kubernetes comic
An air-traffic controller for your containers: you say what you want running, it keeps it that way.
Password hashing & salting comic
Store a fingerprint of the password, with grit mixed in so two alike never match.
Authentication vs authorization comic
Proving who you are at the door, versus what that identity is actually allowed to do inside.
Git merge vs rebase comic
Stitching two histories together with a join, versus replaying your changes on top to make one tidy line.
Hashing vs encryption comic
A one-way fingerprint you can never reverse, versus a locked box you can reopen with the right key.
When the intuition lands, read the real thing.
Every explainer links to its full counterpart — a how-it-works guide, an interactive simulator, or a side-by-side comparison. The analogy gets you in the door; the deep page makes it stick. 62 of them come with a comic you can share.