What is an LLM? A Large Language Model is a neural network trained on massive text data (books, code, websites) that learns to predict the next token in a sequence. That's it at its core — a very sophisticated autocomplete. But "predicting the next word" at scale produces emergent abilities: reasoning, coding, translation, summarization — things nobody explicitly programmed. WHY this matters for you: Every major tech company is integrating LLMs into their products. As a Engineer, you'll be expected to make architectural decisions about when, where, and how to use them. Interviewers will test whether you understand the trade-offs, not just the hype.