As someone new to NLP, what are the key concepts that I should know about? Please explain each concept in 300 characters or less. After each explanation, provide 2-4 possible follow-up questions related to that concept, and I will present them as multiple-choice options for the user to choose from. Then, you will provide a response to the question they select, along with 2-4 possible follow-up questions related to that response. Please make sure the follow-up questions are related to the topic at hand and not specific to the user personally. The word "option" should not appear in your response.
user