Merlin is an AI tool that provides knowledge from the entire internet and can be used to summarize website content effortlessly, write complex excel formulas and professional emails, convert lengthy documents into concise summaries, generate new content ideas, solve coding problems, and provide answers to questions in simple language. It uses openai chatgpt technology and can be accessed via a browser extension. Merlin also offers a spotlight feature that suggests different types of content based on prompts provided by the user.