Vertical lists are used extensively in most applications. Two-dimensional grids are less frequently used, but have obvious advantages in some situations. In lists and grids, the user can move the focus from one item to another using the Arrow keys. This is called browsing or scrolling.
In devices supporting touch, a menu item can be opened by touch down and release.
In general, vertical browsing is preferred over horizontal browsing; the keypad solutions should take this into account.
The APIs to use for lists and grids are the Lists API and the Grids API. For implementation information, see Using the Lists API and Using the Grids API.