Slideshare.net is a website for sharing presentations, documents, and PDFs that has over 25 million monthly visitors. It was started in 2006 by founders with experience at companies like MindCanvas, CommerceOne, and PepsiCo, and is advised by Guy Kawasaki. Slideshare allows free uploading of files up to 100MB and provides embed codes so presentations can be shared on other websites. It also integrates with tools like Google Docs, Firefox plugins, and the Blackboard learning management system.