What is transfer learning, and how do you decide whether to freeze, fine-tune, or use feature extraction?

Transfer learning is the reason you seldom train from scratch, and the real question is how much of the pretrained model to reuse versus adapt. What matters is a clean decision grid across data size and task similarity, plus knowing when a low LR guards against catastrophic forgetting.

Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.