The AI Lexicon

Your friendly guide to AI terms — short, plain-English definitions so you can learn fast and use them with confidence.

A

Artificial General Intelligence (AGI)

Future AI

A hypothetical AI that can learn and reason across any subject as well as a human — still a goal, not a reality today.

AI Agent

Technology

An autonomous system that perceives its environment, makes decisions, and takes actions to achieve goals — the next frontier beyond chatbots.

Algorithm

Concept

A clear set of steps or rules a computer follows to solve a problem. Think of it as a recipe for a task.

Alignment

Ethical AI

Making sure an AI's goals and behavior match human values and intentions — so it does what people want in safe ways.

Annotation

Data

Adding labels to data (like tagging images or marking text) so AI models can learn what things are.

Attention Mechanism

Architecture

A technique that lets models focus on the most relevant parts of their input, enabling breakthroughs in translation, generation, and understanding.

B

Backpropagation

Technology

A method neural networks use to learn from errors: the model adjusts its internal numbers so future guesses get closer to the right answer.

Bias

Ethical AI

When an AI makes unfair or skewed decisions because the data it learned from was unbalanced or flawed.

Black Box

Concept

A system that's hard to inspect or explain — you can see inputs and outputs, but not the internal reasoning easily.

C

Chatbot

Tool

A program that chats with users in text or voice — from simple scripted bots to advanced conversational AIs.

Classification

Concept

Assigning inputs into categories, like sorting emails into "spam" or "not spam."

Computer Vision

Technology

Teaching computers to see and interpret images or videos — used for faces, objects, driving, and more.

D

Data

Core

Raw facts (text, images, numbers) we feed to models so they can learn — quality data matters a lot.

Deep Learning

Concept

A type of machine learning that uses layered neural networks to learn complex patterns from large datasets.

Diffusion Model

Generative

A generative technique that makes images by gradually turning random noise into a clear picture guided by learned patterns.

E

Embeddings

Representation

Numbers that represent words, sentences, or images so a model can compare meaning and find similarities easily.

Encoder

Model

A part of a model that converts input (like words or pixels) into a compact internal representation the AI can use.

Evaluation

Practice

Testing a model to see how well it performs — usually using held-back data not seen during training.

F

Feature

Data

An individual measurable property or input (like age or pixel brightness) used by a model to make predictions.

Fine-Tuning

Technique

Taking a pre-trained model and training it further on specific data so it performs better for a certain task.

Foundation Model

Concept

A very large pre-trained model that can be adapted to many tasks — like a reusable base model.

G

GAN (Generative Adversarial Network)

Architecture

Two networks compete — one makes images, the other checks them — improving realism over time.

Generative AI

Technology

AI that creates new content — like text, images, or music — rather than just analyzing what's already there.

GPU (Graphics Processing Unit)

Hardware

Fast processors used to train and run AI models, especially where many calculations happen in parallel.

H

Hallucination

Behavior

When an AI confidently produces incorrect or made-up information — a common issue with generative models.

Hidden Layer

Neural Net

Intermediate layers in a neural network where features are transformed between input and output.

I

Inference

Process

Using a trained model to make predictions or generate outputs from new input data.

Interpretability

Explainability

How easy it is for humans to understand why a model made a certain decision.

Iteration

Workflow

A single pass of training or improvement — models often need many iterations to learn well.

J

Jaro-Winkler

Similarity

A simple method to measure how similar two strings are — useful for fuzzy matching names or text.

Jitter

Data

Small random changes applied to inputs (like images) during training to help models generalize better.

K

Kernel

Model

In some models, a function that measures similarity between data points (common in methods like SVMs).

K-Fold Cross-Validation

Evaluation

A way to test model performance by splitting data into K parts and rotating which part is used for testing.

L

Large Language Model (LLM)

Technology

A model trained on huge amounts of text to understand and generate natural language (e.g., writing or summarizing).

Learning Rate

Hyperparam

A setting that controls how big each update is during training — too big or too small can cause problems.

Loss Function

Training

A formula that measures how wrong a model's predictions are — training tries to make this number small.

M

Machine Learning (ML)

Field

Building systems that learn from data to make predictions or decisions without being explicitly programmed for every case.

Model

Core

The trained result of a learning process — the thing you use to make predictions or generate outputs.

Multimodal AI

Capability

Models that can understand and combine different kinds of data — like text, images, and audio — at the same time.

N

Natural Language Processing (NLP)

Field

The area of AI focused on making computers understand and generate human language.

Neural Network

Architecture

A set of connected layers that pass information and learn patterns — loosely inspired by the brain's neurons.

O

Optimizer

Training

An algorithm (like Adam or SGD) that updates a model's parameters to reduce the loss during training.

Overfitting

Problem

When a model learns training details too closely and performs poorly on new, unseen data.

P

Pretraining

Process

Training a model on broad data first so it learns general patterns before you fine-tune it for a specific job.

Prompt

Interface

The instruction or question you give to a generative model to guide its output.

Prompt Engineering

Skill

Crafting prompts in a way that helps models give better, more useful answers.

Q

Q-Learning

Reinforcement

A reinforcement learning method where an agent learns which actions give the best future rewards.

Quantization

Optimization

Making a model smaller and faster by using fewer bits for its numbers — useful for running models on phones or edge devices.

R

Regression

Task

A prediction task where the model estimates continuous values, like predicting house prices.

Regularization

Technique

Methods to prevent overfitting, such as adding penalties or randomly dropping parts of the model during training.

Reinforcement Learning

Method

Training agents by reward and punishment so they learn to make sequences of good decisions over time.

RLHF (Reinforcement Learning from Human Feedback)

Technique

A training technique where human preferences guide an AI model's behavior, making outputs more helpful, harmless, and honest.

S

Singularity

Future

A speculative idea where AI growth accelerates to a point of dramatic change — debated and uncertain.

Stochastic Gradient Descent (SGD)

Optimizer

A basic optimization method that updates model parameters using small batches of data at a time.

Supervised Learning

Paradigm

Training models on labeled examples so they learn to map inputs to known outputs.

T

Token

NLP

A piece of text the model processes (often a word or part of a word). Models read tokens one by one.

Training Data

Data

The examples used to teach a model — better, more diverse data usually means a better model.

Transfer Learning

Technique

Reusing a model trained on one task as the starting point for a different task — saving time and data.

Transformer

Architecture

A neural structure great at handling sequences (like text) using attention — it's behind most modern language models.

U

Unsupervised Learning

Paradigm

Letting models find patterns in unlabeled data on their own, like clustering similar items together.

Utility

Concept

A measure used in some AI approaches (notably reinforcement learning) to score how desirable outcomes are.

V

Validation Set

Evaluation

A slice of data used during training to check how well the model is learning and to tune settings.

Vector Database

Infrastructure

A specialized database designed to store and quickly search high-dimensional vectors (embeddings), powering semantic search and RAG systems.

Vision Transformer (ViT)

Model

A transformer adapted for image tasks — it treats patches of an image like tokens of text.

W

Weight

Neural Net

Numbers inside a model that get updated during training — they determine how inputs map to outputs.

Word Embedding

NLP

A vector that represents a word's meaning so similar words are close together in math space.

X

XAI (Explainable AI)

Explainability

Tools and methods that help people understand how AI makes decisions — important for trust and verification.

XGBoost

Algorithm

A fast, powerful machine learning library for structured data — often used in competitions and industry.

Y

YAML

Format

A human-friendly text format often used to store configuration for ML experiments and deployments.

YOLO (You Only Look Once)

Object Detection

A real-time approach to identify objects in images quickly — popular for fast vision tasks.

Z

Zero-Shot Learning

Capability

When a model performs a task it wasn't explicitly trained on by generalizing from related knowledge.

Zeitgeist

Context

In AI, refers to the current trends, tools, and public discussion shaping how AI is understood and used.