Slideshare is a free online platform that allows users to upload and share presentations publicly or privately. Users can upload presentation files from PowerPoint or other formats up to 20MB in size. Uploaded files are converted to Flash format for viewing online without transitions between slides. The platform allows users to tag and organize uploaded files, embed YouTube videos, and add audio to create webinars. Users can delete uploaded files by logging into their Slideshare account, selecting files from their uploads page, and clicking the delete button.