Nepenthes is a tarpit designed to catch and slow down web crawlers, particularly those used for training AI models, by generating endless sequences of pages with random links and content. The software is intended to waste the crawlers' time and resources, and can be configured to work behind a web server like nginx or Apache. It uses a Markov chain to generate text and can be customized with different templates and settings. The author warns that using Nepenthes may cause a website to disappear from search results, as it cannot differentiate between legitimate search crawlers and AI model trainers.