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