One example could be to copy a nicely formatted html table into a rich text editor. It is possible to copy the html manually by looking at the source code, finding the code and text that should be copied and pasting that code into another application.

Copy Code on the other hand automates the process. After installing the Firefox add-on it is simply a matter of selecting the text on the website that should be copied, right-clicking when that is done and choosing the Copy HTML entry from the menu.

The Copy Code add-on for Firefox is a experimental add-on which means that users who want to install it need to log into the Mozilla website first.

Update: Copy Code has been discontinued. Firefox users can take a look at the Copy HTML add-on which provides a similar functionality.