Core Concepts

Neural Module

Neural Modules are building blocks for Models. They accept (typed) inputs and return (typed) outputs. All Neural Modules inherit from ``torch.nn.Module`` and, therefore, compatible with PyTorch ecosystem. There are 3 types on Neural Modules:

  • Regular modules
  • Dataset/IterableDataset
  • Losses


NeMo Model is an entity which contains 100% of information necessary to invoke training/fine-tuning. It is based on Pytorch Lightning’s LightningModule and as such contains information on:

  • Neural Network architecture, including necessary pre- and post- processing
  • How data is handled for training/validation/testing
  • Optimization, learning rate schedules, scaling, etc.

Neural Types

Neural Types perform semantic checks for modules and models inputs/outputs. They contain information about:

  • Semantics of what is stored in the tensors. For example, logits, logprobs, audiosignal, embeddings, etc.
  • Axes layout, semantic and (optionally) dimensionality. For example: [Batch, Time, Channel]