What problem does it solve? Machine learning teams lose track of experiments, hyperparameters, and model versions when training runs are scattered across notebooks and scripts. This Skill provides complete guidance for using Weights & Biases (W&B) to log metrics automatically, visualize training in real time, optimize hyperparameters with sweeps, and version datasets and models with full lineage. ## Core Features & Use Cases - Experiment Tracking: Initialize runs with wandb.init, log metrics, configs, media, and system stats, and compare runs in real-time dashboards. - Hyperparameter Sweeps: Run grid, random, or Bayesian optimization searches with early termination (Hyperband) and parallel agents across GPUs. - Artifacts & Model Registry: Version datasets and models with automatic lineage tracking, aliases for deployment stages, and a central model registry. - Framework Integrations: Native support for PyTorch, PyTorch Lightning, HuggingFace Transformers, Keras/TensorFlow, Fast.ai, XGBoost, and LightGBM. - Use Case: A data scientist fine-tuning a BERT model can launch a Bayesian sweep over learning rate and batch size, let W&B terminate weak runs early, and promote the best checkpoint to a production model registry. ## Quick Start Set up a W&B tracked training run for my PyTorch script that logs loss and accuracy each epoch and saves the final model as an artifact.