# Glossary

| Term | Meaning |
| --- | --- |
| Inference | Using a trained model to convert a recording. |
| Checkpoint | File containing learned model weights. Resume checkpoints and inference exports have different roles. |
| Embedder | Component that extracts a representation of the source audio for the conversion engine. |
| Index | Optional collection of learned feature vectors used during retrieval. |
| Index ratio | How strongly an implementation uses retrieved features during conversion. |
| F0 | Fundamental frequency, used to represent pitch over time. |
| Pitch extractor | Algorithm that estimates F0 from a recording. |
| Semitone | One twelfth of an octave. A change of 12 semitones is one octave. |
| Vocoder | The part of the pipeline that generates the waveform from its conditioning inputs. |
| Sample rate | The number of audio samples per second. It is distinct from model version and pitch transposition. |
| Pretrain | Starting weights used when training a new model. |
| Epoch | One pass through the training dataset in the usual training setup. |
| Step | A training update. Batch size and dataset size affect the relationship between steps and epochs. |
| Stem | One isolated part of a mix, typically a vocal or instrumental. |
| Latency | The time between an input event and its audible output. |

See [RVC fundamentals](../start/rvc-fundamentals.md), [Models and files](../start/models.md) and [Training](../model-training/training.md) for these terms in context.