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Few-shot prompting

Including examples of what you want in your prompt so the AI matches the pattern. “Translate to French. English: hello → French: bonjour. English: goodbye → French: ?” is few-shot prompting (with one example). Often dramatically better than describing what you want abstractly. Zero-shot = no examples; one-shot = one; few-shot = a handful.

See also: Prompt engineering, AI prompting cheat sheet


Fine-tuning

Taking a pre-trained AI model and training it further on your specific data to specialise it. Less common than it used to be — modern models with good prompting and RAG often beat fine-tuned models without the cost and complexity. Still useful for: matching a specific style, learning domain jargon, or running smaller specialised models cheaply at scale.

See also: Fine-tuning vs context, RLHF


Fetch

The modern built-in way to make HTTP requests from JavaScript. Available in browsers and in Node 18+. Returns a Promise.

const res = await fetch("/api/users");
const users = await res.json();

See also: HTTP, Async, APIs


Feature flag

A switch that lets you turn a feature on or off without redeploying code. “Show the new dashboard only for users in beta” is a feature flag. Useful for gradual rollouts, A/B tests, and quickly killing broken features. Services like LaunchDarkly, GrowthBook, and PostHog provide feature flag infrastructure; simple flags can also just be environment variables.

See also: Environment variables


Framework

A library that imposes a structure on how you build an app. The framework calls your code, rather than you calling its code. Next.js is a framework: it has opinions about routing, rendering, and file organization that you have to follow. React, by contrast, is technically a library — you can use it however you want.

See also: Next.js, React, Library


Frontend

The part of an application that runs in the user’s browser. HTML, CSS, JavaScript, the React components — all frontend. The opposite half is the backend.

See also: Frontend (section)


Function

A reusable named block of code that takes inputs and (usually) returns an output. The fundamental unit of programming. Functions can call other functions, including themselves (see recursion).

function add(a, b) {
  return a + b;
}

See also: JavaScript


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