Glossary

Short definitions for the terms in this guide. Each entry links to the page that explains it in context.

Terms

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Acceptance rate Serving
The share of proposed draft tokens that the main model accepts. It affects how much speculative decoding speeds things up. Read more
Activation Foundations
A set of numbers produced by a model layer for a particular input. Read more
Admission control Serving
A way for a server to limit incoming work. It may make requests wait or turn them away when it is full. Read more
Attention Foundations
A way for a model to use information from other tokens when it processes a token. Read more
Autoregressive Foundations
Describes a model that generates an output one token at a time, using earlier tokens to choose the next one. Read more
Batch Serving
A group of requests or examples processed together. A bigger batch can improve total throughput but increase the wait for each request. Read more
BF16 Serving
A 16-bit floating-point format with a wide exponent. It is common for training and for unquantized serving. Read more
Bits per weight Compression
How much space one model weight uses, including its share of any scales and metadata. Read more
Byte-pair encoding (BPE) Foundations
A tokenizer method that repeatedly merges frequent pairs of pieces. Byte-level versions start from bytes. The learned pieces form a fixed vocabulary. Read more
Calibration Compression
Using sample data to choose settings for quantization. The sample should resemble the work the model will do. Read more
Capacity factor Serving
A setting used by some MoE implementations to limit assignments to an expert. Overflow handling varies. Read more
Catastrophic forgetting Training
The loss of earlier skills after training on a narrow dataset. Read more
Causal mask Foundations
A rule that stops a token from using information from later tokens when predicting the next token. Read more
Checkpoint Foundations
A saved copy of a model’s learned weights. It may also include the settings and other files needed to load it. Read more
Chunked prefill Serving
Splitting a long prompt into pieces so a server can work on other requests between pieces. Read more
Classifier-free guidance (CFG) Media
A diffusion technique that pushes the result toward the prompt. A high scale can oversaturate the output. Read more
Coalescing Serving
Arranging threads so neighboring threads read neighboring addresses. Poor coalescing wastes memory sectors. Read more
Contamination Measurement
Test data that leaked into training. It can make a benchmark score look better than the model's real skill. Read more
Context copies Serving
A draft method that copies a suffix from the prompt or cache and verifies it. It helps edits and repeated text. Read more
Context window Foundations
The amount of text a model can use at once, measured in tokens. The prompt and the reply both need space. Read more
Continuous batching Serving
Adding and removing requests as the model runs, instead of waiting for a whole fixed group to finish. Read more
CUDA Serving
NVIDIA's programming model for GPU kernels. Kernels run as grids of thread blocks. Read more
Decode Serving
The part of a request where a model writes its answer, usually one token at a time. Read more
Diffusion Media
A way to make images or video by starting with noise and gradually changing it into a result. Read more
Distillation Training
Training a smaller or faster model using another model as a teacher. Read more
DPO Training
Direct preference optimization. It trains on pairs of preferred and rejected answers with a simpler loss than RLHF. Read more
Draft token Serving
A guessed next token that the main model checks before using it. Read more
Embedding Foundations
A list of numbers the model uses to represent a token. Read more
EXL3 Compression
A trellis-coded weight format with a configurable bit budget. It needs compatible ExLlamaV3 kernels. Read more
Expert Serving
A learned part of a mixture-of-experts model. A router chooses which experts work on each token. Read more
Expert parallelism Serving
Splitting experts across devices. Tokens move over an all-to-all link to reach their expert. Read more
Fine-tuning Training
Extra training that changes an already trained model for a particular job or behavior. Read more
FP16 Serving
A 16-bit floating-point format. It is common for weights, activations, and KV caches. Read more
FP8 Compression
A family of 8-bit floating-point formats. The value payload is half the size of FP16; scales and other metadata add storage. Read more
GGUF Compression
A model file format used by llama.cpp. It stores quantized tensors and metadata for local serving. Read more
Goodput Measurement
The number of requests that finish within the chosen service target. Define how rejected requests count too. Read more
Gradient Training
Numbers that tell the optimizer how the loss changes when it changes each weight. They help it choose which way to move. Read more
Grouped-query attention (GQA) Foundations
An attention design in which several query heads share key and value heads. This can make the KV cache smaller. Read more
Hallucination Foundations
An answer that sounds convincing but is wrong or not supported by the available information. Read more
Held-out set Measurement
Examples kept separate from training and tuning, used to test how well a model handles new inputs. Read more
Inference Serving
Using a trained model to process an input and produce an output. Read more
Inter-token latency (ITL) Serving
The time between output tokens in a streamed answer. Read more
Kernel Serving
A small program that runs on a GPU. Kernels perform tasks such as matrix multiplication or attention. Read more
Kernel fusion Serving
Combining several operations into one kernel so intermediate tensors stay on chip instead of going to global memory. Read more
KV cache Serving
Saved keys and values from earlier tokens. The model reuses them when it writes new tokens, which saves work but uses memory. Read more
KV paging Serving
Storing the cache in fixed-size pages so the scheduler can allocate, share, and evict it without copying a whole sequence. Read more
Latency Serving
The time an operation or request takes, measured from a defined start to a defined end. Read more
Load-balancing loss Training
A training term that discourages the router from sending most tokens to a few experts. Read more
Logits Foundations
Raw scores for each vocabulary token before softmax. Sampling turns them into a choice. Read more
LoRA Training
A fine-tuning method that keeps the original model weights fixed and trains a small set of additional weights. Read more
Loss Training
A number that measures how far a model’s prediction is from the desired result. Training tries to reduce it. Read more
Memory bandwidth Serving
The bytes a device can move per second. It can limit decode speed when memory traffic is the bottleneck. Read more
Memory wall Serving
A speed limit caused by how quickly a device can move data to and from memory. Read more
Mixture of experts (MoE) Serving
A model with many learned parts called experts. A router chooses a few experts to process each token. Read more
Multi-head latent attention (MLA) Foundations
A compressed attention cache design. It reduces the bytes per token compared with a standard KV cache. Read more
Multi-query attention (MQA) Foundations
An attention layout with one key and value head shared by all query heads. It uses less cache than otherwise identical multi-head attention. Read more
Multi-token prediction (MTP) Serving
A training approach that adds predictions for tokens beyond the next one. Some models use those predictions to draft tokens. Read more
MXFP4 / MXFP8 Compression
Block-scaled float formats with a shared scale for 32 values. They are an open standard with new kernel support. Read more
NVFP4 Compression
A 4-bit float format with FP8 block scales, used on Blackwell hardware. It stores about 4.5 bits per weight. Read more
Occupancy Serving
The share of a multiprocessor’s maximum warp capacity that is active. Registers and shared memory can limit it. Read more
Overfitting Training
When a model fits its training examples so closely that it does worse on new examples. Read more
Parameter Foundations
A learned number in a model. Parameters are often called weights. Read more
Perplexity Measurement
The exponent of cross-entropy on a text set. It measures fit, not task quality. Read more
Pipeline parallelism Serving
Splitting layers into stages across devices. It adds a pipeline bubble and needs enough requests to fill the stages. Read more
Prefill Serving
The stage where a model reads the prompt and saves information needed to write an answer. Read more
Prefix cache Serving
Saved information for the beginning of a prompt that can be reused when another request starts with the same text. Read more
Q4_K_M Compression
A GGUF 4-bit k-quant mix at about 4.5 bits per weight. Some tensors stay wider than others. Read more
QLoRA Training
LoRA on a 4-bit base model. It cuts the base memory by about four times. Read more
Quantization Compression
A way to store numbers using fewer bits. It can save memory, but the stored numbers may be less exact. Read more
Quantization-aware distillation (QAD) Compression
Training a low-bit student to match a high-precision teacher. It can recover quality at a training cost. Read more
Quantization-aware training (QAT) Compression
Simulating low precision during training so the model learns to tolerate the error. Read more
RLHF Training
Reinforcement learning from human feedback. It trains a policy against a reward model built from preference data. Read more
Roofline Serving
A model that compares compute and bandwidth limits against arithmetic intensity. Read more
Router Serving
The part of a mixture-of-experts model that chooses which experts work on each token. Read more
Sampling Foundations
Choosing the next token from the model’s probability distribution. Settings such as temperature affect the choice. Read more
Softmax Foundations
A function that turns a list of scores into probabilities that add up to one. Read more
Speculative decoding Serving
Guessing several tokens and having the main model check them together. It can speed up generation when enough guesses are useful. Read more
Step cache Media
Reusing features across diffusion steps to cut run time. It changes the output and needs a quality check. Read more
Supervised fine-tuning (SFT) Training
Training on input-output pairs, usually with the loss on the assistant tokens. Read more
Tensor core Serving
A GPU unit for fast matrix work. Kernels must feed it the right tile shapes and data types. Read more
Tensor parallelism Serving
Splitting a matrix across devices. It adds an all-reduce exchange to every layer. Read more
Throughput Serving
How much work a system completes in a given time, such as tokens or requests per second. Read more
Time to first token (TTFT) Serving
Time to first token: the wait from sending a request until the first piece of the answer arrives. Read more
Token Foundations
A piece of text that a tokenizer maps to a number. One word can be one token or several. Read more
Tokenizer Foundations
A tool that splits text into tokens and converts those tokens to numbers and back. Read more
Top-k sampling Foundations
Sampling from the k most likely tokens. It cuts the tail of the distribution. Read more
Top-p sampling Foundations
Sampling from the smallest set of tokens whose probability adds up to p. Read more
Transformer Foundations
A stack of attention and feed-forward layers. It is the base architecture for most language models. Read more
VAE Media
An encoder and decoder for latent media models. It compresses images or video before diffusion. Read more
Verification Serving
The target model's check of draft tokens. A correct rule keeps the output distribution unchanged. Read more
Warmup Measurement
An initial run that loads weights and warms caches before measurement. Read more
Weight Foundations
A learned number in a model. The model uses its weights to turn an input into a prediction. Read more

The glossary is a map, not a specification. When a definition matters for a decision, read the linked page and the model card.