The Stack Dictionary · 105 terms · 8 topics
Stack terms,
for builders.
Every piece of the stack explained with an analogy — for students, vibe coders, and hackathon nights. Then pick it in the builder and ship.
Why this exists
The builder asks you to pick a frontend, an ORM, an API layer. Those words are the whole product — and they're also why people bounce. Academy is the glossary we wanted for the student cramming a stack, the vibe coder mid-prompt, and the team with a deadline: one term, one analogy, no lecture. Once you have the words, you can ask better questions. Once you can ask better questions, you can ship the idea.
The one to read first
Stack
The combo of tools your app is built from.
Read Stack →
$define--plain-english
The Basics
6 termsHow AI Works
14 terms- Context WindowHow much your AI can hold in mind at once.
- HallucinationWhen AI sounds confident and is just wrong.
- TokenThe unit AI reads and writes in.
- Prompt CachingPay once to read it, reuse it cheaply.
- SessionOne continuous conversation with your AI.
- CompactionSummarizing the chat so it keeps fitting.
- EmbeddingMeaning turned into a list of numbers a computer can compare.
- Vector DatabaseStorage that finds things by meaning, not exact words.
- RAGThe open-book exam: look it up, then answer.
- Fine-tuningSending the model back to school on your examples.
- TemperatureThe dial between a careful clerk and a jazz solo.
- InferenceThe moment the model actually answers.
- ReasoningLetting the model work a problem before it blurts.
- MultimodalA model that can take more than text — images, audio, video.
Building With AI
19 terms- AgentAn AI that takes actions, not just answers.
- MCPA universal plug for your AI's tools.
- System PromptThe standing instructions your AI always follows.
- SkillA saved recipe your AI can follow on demand.
- CLAUDE.mdThe house rules your AI reads before it starts.
- Slash CommandA keyboard shortcut for a whole prompt.
- HarnessThe car built around the AI engine.
- Computer UseAI that clicks and types like a person at the desk.
- Agents SDKA starter kit for building your own AI worker.
- Voice AgentsAn agent you talk to out loud.
- OAuthA valet key for an account — not the master key.
- Vibe CodingBuilding by describing it and letting AI write the code.
- Permission ScopeExactly which doors a key is allowed to open.
- Tool CallingThe line between a chatbot and an agent is tools.
- Prompt InjectionHostile instructions hiding in the text you asked the AI to read.
- EvalA test that tells you if the change helped or quietly hurt.
- GuardrailsLimits you put on an AI before it does something dumb.
- SandboxA playpen so the agent can be wrong without wrecking the house.
- Progressive DisclosureShow the short version. Keep the depth one step away.
Code & Collaboration
10 terms- GitSave points for your code.
- CommitA labeled snapshot you can return to.
- BranchA safe copy of the project to try changes on.
- GitHubWhere the code lives and gets shared.
- Pull RequestA proposed change, put up for review.
- Open SourceCode anyone can read, use, and improve.
- MarkdownPlain text that formats itself.
- DependencySomeone else's code you install so you don't rebuild the wheel.
- MergeFolding one branch back into another — and the fight when both changed the same line.
- ForkYour own full copy of someone else's project.
APIs & Connections
18 terms- APIHow your app — and your AI — talk to other software.
- AuthHow your app knows who someone is.
- DatabaseThe cabinet software talks to, so tomorrow isn't empty.
- ORMA translator between your code and the database.
- SDKA toolkit for building on someone else's service.
- WebhookAn app that pings you the moment something happens.
- EndpointOne specific address on an API.
- RESTThe common rulebook most HTTP APIs follow.
- HTTP MethodsGet, create, update, delete — the verbs of the web.
- Env FileWhere secret keys live, out of the code.
- SchemaThe promised shape of the data — labeled boxes, each a type.
- JSONThe little note card almost every API writes on.
- YAMLJSON's cousin that humans can stand to edit.
- SecretA string that must stay hidden or someone else can act as you.
- Rate LimitA bouncer that says you asked too many times.
- CORSThe browser asking the other site if your page is allowed to call it.
- CookieA small note the browser keeps and sends back to that site.
- EncryptionScrambling data so the machines in the middle only see noise.
Shipping & Running
25 terms- DeployOpen the doors so other people can use it.
- HeadlessSoftware that runs with no screen, nobody watching.
- CronAn alarm clock that runs a job on a schedule.
- DNSThe internet's phone book for names.
- CDNCopies of your static files kept close to each visitor.
- Object StorageA giant bucket on the internet for files.
- ServerlessRent a computer for a moment, not a month.
- EdgeRunning code near the user instead of in one faraway basement.
- WorkerA small program that runs one job on demand.
- RuntimeThe engine that actually runs your code.
- ProcessOne running instance of a program — a living copy, not the file.
- DaemonA process that stays on in the background. Not a demon.
- QueueA line of work so fast things don't trample each other.
- JobOne specific piece of work sitting in a queue.
- StateThe stuff the app has to remember while it's running — and after.
- CacheA nearby copy so you don't walk to the walk-in every time.
- SSHA secure terminal on a computer you are not sitting at.
- BuildTurning source into the thing you actually run or ship.
- StagingA dress rehearsal of production, with fake or extra-careful data.
- RollbackPutting the last good version back on stage.
- DockerA sealed box that runs the same way on every machine.
- Feature FlagA switch in the live app that hides a feature without a new deploy.
- TestA script that checks the code still does the thing after you touch it.
- CI/CDA robot that tests, builds, and ships every time you push.
- The CloudSomeone else's computers, rented by the hour and reached over the internet.
Debugging & Errors
7 terms- TraceA map of where the time went when the app felt slow.
- Type ErrorThe compiler refusing a shape it did not agree to.
- Stack TraceThe list of calls the program was in when it crashed.
- LogA receipt printer that never stops.
- BugWhen the software does the wrong thing and everyone calls it a bug.
- PatchThe small change that fixes the bug.
- LatencyThe beat between the click and the thing happening.
How Developers Think
6 terms- DRYWrite it once. Reuse it everywhere.
- YAGNIDon't build what you don't need yet.
- KISSKeep it simple. Skip the clever version.
- RefactoringTidying the code without changing what it does.
- Technical DebtShortcuts now that you pay interest on later.
- AsyncWork that runs without making everything else wait in line.