SlideShare is a website that allows users to upload and share presentations, documents, PDFs, videos and webinars. It has over 60 million monthly visitors, making it one of the most visited websites globally. By creating a SlideShare account and uploading files, teachers can add PowerPoint presentations to their Moodle page for students to browse without having to open the file directly. The document provides instructions on how to sign up for a free SlideShare account and upload files to share.