I was just looking at a question on Stack Overflow and thought it could really use a generic shadow-box tag, but it seems the tag shadowbox is being used for a particular plugin of that name (shadowbox.js). However, a shadowbox is also a well known web structure for viewing content originating from before their use in web pages. This blog post Shows how prevalent the structure is (under a synonym, light box)
Disclaimer: This is my first question of this type and I really have no idea what I'm doing. Please feel free to correct me where necessary.