Bookmark Any Web Page with a Single Keystroke

How do you bookmark a Web site? Most users venture into the Bookmarks menu, click Add to Favorites (or something similar), and so on. It can add up to a lot of clicking.
There's a faster, easier, smarter way: Just use the keyboard shortcut. Here's the keystroke for all popular browsers:
Chrome: Ctrl-D
Firefox: Ctrl-D
Internet Explorer: Ctrl-D
Opera: Ctrl-D
Safari: Ctrl-D