What is a drop down menu?

A drop down menu is an element in graphical user interfaces that includes a drop-down list for controlling certain actions/options/inputs.

drop down menu is a set of options enlisted on a window that will appear once you click on the downward arrow, found on the right side of the main window.

Drop down menu is a menu that appears on the screen when clicking on a button or text selection.
For example, many programs will have a "File" drop down menu at the top left of their screen.
Clicking on the "File" text generates a new menu with additional options.

A drop down menu is horizontal list of options that each contain a vertical menu. When you roll over or click one of the primary options in a drop down menu, a list of choices will "drop down" below the main menu.

The most common type of drop down menu is a menu bar. On Windows systems, the menu bar is typically located at the top of each open windows. On Macintosh systems, it is fixed at the top of the screen. When you click one of the options in the menu bar, such as "File", a list of options will appear below the menu, such as New, Open, Close, and Save. You can click any of these options to select it.

Drop down menus are also commonly used for website navigation. Many websites use drop down menus to provide users with direct links to more pages than standard navigation bars allow. For example, a news website may list several news categories in the main menu, such as Politics, Business, Sports, and Entertainment. Each of these menu options may include several subcategories. For example, the Sports menu may contain options such Baseball, Basketball, Football, Hockey, and Soccer. By selecting a specific sport within the Sports menu, you can navigate to the section you want with one click, instead of having to visit the main Sports page first.

Website drop down menus are typically created using DHTML (dynamic HTML), which may include a combination of HTML, CSS, and JAVASCRIPT code. They can also be written as FLASH applications. While software program menus typically require you to click on the main menu to reveal the drop down options, website drop down menus often appear when you simply move the Cursor over the main menu. Clicking a main menu option at the top of a website drop down menu may open the main topic page (like the Sports page in the example above). Regardless of how intuitive you find drop down menus to be, they can be a useful navigation tool once you get used to them.