The document summarizes three popular social media platforms - Facebook, Pinterest, and Instagram. Facebook allows users over 13 to connect with friends and share photos, videos, and updates. Pinterest is a social bookmarking site where users over 13 can pin crafts, recipes, and other ideas. Instagram is a media sharing app for users over 13 to edit and share photos and videos from their smartphones or tablets. Each platform has privacy settings and rules against offensive or inappropriate content.