Perplexity AI is a conversational search engine that uses large language models to provide direct answers to queries by pulling information from the web in real-time and citing sources. It is designed as an alternative to traditional search engines, summarizing information from multiple sources into a concise response. Unlike ChatGPT, which is a general-purpose conversational AI, Perplexity AI focuses on factual queries and research. Perplexity AI is known for its accuracy and reliability, due to its access to real-time data. It also offers features such as an internal knowledge search and the ability to create customized knowledge spaces.