AI Technical Glossary: A Complete Guide to 270+ Terms

blog@baifan.site (ByF (BaiFan)) — Wed, 30 Jul 2025 14:00:00 +0800

AI Technical Glossary
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This reference gathers the core terminology of the LLM field, from basic concepts to advanced technical architecture, to help you build a systematic understanding of the AI technology landscape.

📚 Fundamentals
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Term	Technical definition	Plain-language explanation	Example
AGI (Artificial General Intelligence)	An AI system with human-level intelligence	An all-capable AI that can think, learn, and create like a person	A robot that can write poetry, code, cook, and chat at the same time
LLM (Large Language Model)	A large neural network model trained on massive data	A “super brain” that understands and generates human language	GPT-4, Claude, ERNIE Bot, and the like are all LLMs
Training	The process of fitting neural network parameters on large data	The AI’s “study phase” — like a person absorbing knowledge from books	Training a model on all text on the internet until it learns language
Inference	A trained model generating output from input	The AI’s “application phase” — like a person answering questions from what they learned	The model generating an answer after you ask it a question
Token	The smallest unit of text a model processes, a fragment split by a tokenization algorithm	The particles of AI language, processed one at a time	`"我喜欢苹果"` → `["我", "喜欢", "苹果"]`

🏗️ Architecture
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Term	Technical definition	Plain-language explanation	Example
Transformer	A deep learning architecture based on self-attention, proposed by Google in 2017	The “neural skeleton” of modern AI that lets models understand language efficiently	GPT, BERT, and every other large model is built on Transformer
Encoder	A neural network component that encodes an input sequence into semantic representations	The AI’s “understanding unit” — turns text into vectors machines understand	BERT uses an encoder for text understanding tasks
Decoder	A neural network component that generates output token by token based on context	The AI’s “writing unit” — generates answers from what it understood	The GPT series are all decoder-only models
Self-Attention	A mechanism that computes how much each element in a sequence relates to the others	The AI automatically “focuses on what matters”, like a person picking out key points while reading	In “deposit money at the bank”, “bank” attends to “money”; in “fish by the river bank”, it attends to “river”
Multi-Head Attention	Several self-attention mechanisms run in parallel to capture different types of dependencies	The AI understands text from multiple angles at once	One head tracks syntax while another tracks semantics
Positional Encoding	Vector representations that add position information to each token	Lets the model know “who comes first, who comes later”	“The dog bit the man” and “the man bit the dog” mean different things
Query	The vector that actively asks for related information — what the current word needs	The numeric expression of “what am I looking for”	“Apple” queries attributes like taste and color
Key	The identifier vector for information being queried — what each word can offer	The label of “what I can provide”	“Sweet” serves as the Key for a taste feature, waiting to be queried
Value	The representation vector holding the actual content and true semantic information	“My actual content”, in numbers	The actual semantic representation of “sweet”: `[0.8, 0.2, -0.1]`
Attention Weight	Importance scores expressing how much to attend, usually normalized via softmax	“How much to pay attention”, quantified	0.8 means strong attention, 0.1 weak; all weights sum to 1
Cross-Attention	Attention across two sequences — Query comes from one, Key/Value from another	Cross-modal information exchange	In image-text matching, text Queries attend to image Keys/Values
Causal Attention	Attention restricted to the current position and earlier, preventing future information leaks	Attention that can “only look backward”	When GPT generates the 5th word it can only see the previous 4
Softmax Function	An activation function that turns any real-valued vector into a probability distribution	Converts scores into “importance percentages”	`[2,1,0] → [0.67,0.24,0.09]`, preserving relative magnitudes

🔢 Mathematical Representation
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Term	Technical definition	Plain-language explanation	Example
Vector	A mathematical object with magnitude and direction; an ordered list of numbers	A “numeric ID card” that describes a thing with numbers	`[25, 180, 70]` can represent a person’s age, height, and weight
Embedding	The technique of mapping discrete symbols into a continuous vector space	Turns words into “numeric coordinates”	`"king"→[0.25, -0.12, 0.78, ...]`
Query / Key / Value	The three core vector matrices in self-attention: what is asked, what is labeled, what is delivered	Query = what I want, Key = what I can offer, Value = my actual content	`Query=[0.1,0.2]` asks about taste, `Key=[0.8,0.1]` labels sweetness, `Value=[0.9,0.05]` is the actual representation of sweetness
Feed-Forward Network	Applies an independent nonlinear transform at each position	Deepens the model’s understanding of each word	From “spring” the model further associates “warmth, growth”
Layer Normalization	Standardizes a layer’s inputs	A “stabilizer” for training	Prevents gradient explosion or divergence
Residual Connection	A cross-layer connection that preserves the original information	An “express lane” for information, preventing loss	Like a shortcut path that keeps deep networks from degrading

🔄 Processing Pipeline
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Term	Technical definition	Plain-language explanation	Example
Tokenizer	Converts text into a sequence of tokens	A “knife for chopping text”	`"Hello world" → ["Hello", " world"]`
Context Window	The maximum number of tokens a model can process	The AI’s “memory limit”	GPT-4 has a 128K context
Decoding	Generates text token by token from a probability distribution	The AI’s “writing process”	Starts generating from the most probable word
Temperature	A parameter controlling generation randomness	A “creativity dial”	High temperature is more creative, low more stable
Top-p Sampling	A sampling strategy based on cumulative probability	An “essence filter”	Only considers candidates whose cumulative probability reaches 90%
Max Tokens	Caps the length of generated output	A “word-count limiter”	Keeps the AI from answering too long

🛠️ Engineering Practice
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Term	Technical definition	Plain-language explanation	Example
RAG (Retrieval-Augmented Generation)	An AI approach combining retrieval and generation	An “open-book exam” AI	Look up references first, then answer the question
Prompt Engineering	The craft of designing and optimizing prompts	“The art of asking”	Helping the AI understand your needs better
Fine-tuning	Training a pretrained model on a specific task	“Targeted job training”	Turning a general model into a medical assistant
BPE (Byte Pair Encoding)	A common tokenization algorithm	A “text compression technique”	`"unhappiness" → ["un","happi","ness"]`
Detokenization	Turns a token sequence back into readable text	“Reassembling the pieces”	`["我","喜欢","苹果"]→"我喜欢苹果"`
Streaming	Generates output token by token in real time	The “typewriter effect”	A chatbot thinking while it types

🧠 Classic Models Compared
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Term	Technical definition	Plain-language explanation	Example
RNN (Recurrent Neural Network)	A neural network that processes sequences step by step	A “read-one-word-at-a-time AI”	Translating `"我爱你"` word by word
LSTM (Long Short-Term Memory)	An improved RNN that handles long-range dependencies	“A better memory”	Can remember content from the beginning
CNN (Convolutional Neural Network)	A neural network that excels at image patterns	An “image specialist”	Recognizing cats, dogs, and faces
Encoder-Decoder Architecture	A model containing both understanding and generation modules	An “all-round AI”	Machine translation models

📊 Application Scenarios
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Term	Technical definition	Plain-language explanation	Example
Chat product	A user-facing AI application interface	An “AI chat shell”	ChatGPT, Claude
API call	An interface for program-to-program communication	The “AI phone line”	An application calling the OpenAI API
Context management	The technique of maintaining conversation history	The “AI’s memory”	A chatbot remembers what you said
Multi-turn dialogue	A continuous human-machine interaction mode	“Ongoing conversation”	Ask about the weather, then what to wear
Function Calling	The model invoking external APIs to perform tasks	The “AI’s ability to act”	The AI checks the weather or searches automatically

🧩 Model Optimization and Training Techniques
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Term	Technical definition	Plain-language explanation	Example
LoRA (Low-Rank Adaptation)	Fine-tunes model parameters via low-rank matrices	“Lightweight fine-tuning”	Lets an LLM quickly adapt to a new domain
Quantization	Represents model parameters at lower precision	“Slimming the model down”	FP32→INT8 speeds up inference
Pruning	Removes redundant neurons or connections	“Trimming the branches”	Cutting useless parameters
Distillation (Knowledge Distillation)	A large model teaches a small one	“Teacher trains the student”	GPT-4 teaching a small model
Checkpoint	A saved intermediate state during model training	A “training save point”	Prevents losing progress on a power cut

🔍 Vector Retrieval and Knowledge Integration
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Term	Technical definition	Plain-language explanation	Example
Embedding Model	A model that converts text into semantic vectors	A “semantic coordinate machine”	text-embedding-3-large
Vector Database	A database supporting vector retrieval	A “semantic warehouse”	Milvus, Pinecone, FAISS
Cosine Similarity	Measures how similar two vectors’ directions are	A “semantic similarity meter”	`A cat is sleeping ≈ The cat is resting`
Knowledge Graph	Stores knowledge as nodes and relationships	A “knowledge map”	`apple → is a → fruit`
Hybrid Search	Combines semantic retrieval with keyword matching	“Belt-and-suspenders search”	Searching both `cat` and `pet animal` at once

🧩 Multimodal and Agents
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Term	Technical definition	Plain-language explanation	Example
Multimodal Model	Handles text, images, audio, and other modalities at once	A “full-senses AI”	GPT-4V, Gemini
VLM (Vision-Language Model)	Vision-Language Model	An AI that can “see pictures”	A visual question-answering AI
Speech Recognition	Converts speech to text	A “dictation AI”	Voice input methods
TTS (Text-to-Speech)	Converts text to speech	An “AI announcer”	The AI reads its answer aloud
AI Agent	An AI capable of autonomous action and decision-making	An AI assistant “that can act”	Devin, AutoGPT

⚙️ Model Evaluation and Safety
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Term	Technical definition	Plain-language explanation	Example
Hallucination	The model generating false information	“Confident nonsense”	Inventing papers or facts
Alignment	Bringing the model in line with human values	“Values training”	Tuning a model with RLHF
RLHF (Reinforcement Learning from Human Feedback)	Optimizes a model with human preferences	“Humans teaching AI to speak”	How ChatGPT was trained
Red Teaming	Adversarial testing of model safety	A “security penetration test”	Testing whether the model leaks secrets
Bias	Systematic prejudice in model outputs	“The AI plays favorites”	Preference for a gender or language

🧰 Emerging Trends and Future Directions
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Term	Technical definition	Plain-language explanation	Example
Mixture of Experts	A structure with multiple sub-models activated dynamically	A “panel-of-experts AI”	The `Gemini 1.5 Pro` architecture
Context Compression	Compresses conversation history to save tokens	“Memory compression”	Summarizing long conversations
Memory-Augmented Model	An AI combined with long-term memory mechanisms	An AI “with a memory”	`ChatGPT` long-term memory
Autonomous Agent	An AI that can plan and execute tasks on its own	A “self-managing AI”	`AutoGPT`, `Devin`
Synthetic Data	Virtual training data generated by AI	“AI-made textbooks”	Expanding a training set with AI

💡 Study Advice
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🎯 Priority for Mastering Core Concepts
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Beginner (must know): Token, Embedding, Transformer, LLM
Intermediate (important): Self-Attention, RAG, Context Window
Advanced (optional): LoRA, Mixture of Experts, Red Teaming

📖 Suggested Learning Path
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Understand the basics: what a token is, and why vector representation is needed
Master the core architecture: the Transformer encoder-decoder structure
Practice application techniques: combining prompt engineering with RAG
Go deeper into technical details: attention mechanisms and alignment training

🔗 Concept Map
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1
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Fundamentals → Math → Architecture → Processing → Engineering → Optimization → Retrieval → Agents
↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓
Token → Vector → Transformer → Decoding → RAG → LoRA → Embedding → Agent
LLM → Q/K/V → Attention → Context → Prompt → Quant → Knowledge → Memory

🚀 Tip: the AI technology landscape is vast but tightly interconnected. A good approach is to study it systematically along four dimensions: understand → build → optimize → secure.

Deep Learning on ByF (BaiFan) · Daily Deep Think

AI Technical Glossary: A Complete Guide to 270+ Terms

AI Technical Glossary #

📚 Fundamentals #

🏗️ Architecture #

🔢 Mathematical Representation #

🔄 Processing Pipeline #

🛠️ Engineering Practice #

🧠 Classic Models Compared #

📊 Application Scenarios #

🧩 Model Optimization and Training Techniques #

🔍 Vector Retrieval and Knowledge Integration #

🧩 Multimodal and Agents #

⚙️ Model Evaluation and Safety #

🧰 Emerging Trends and Future Directions #

💡 Study Advice #

🎯 Priority for Mastering Core Concepts #

📖 Suggested Learning Path #

🔗 Concept Map #