The iPad is based on the same iOS (first called iPhone OS) operating system used by the iPhone smartphone and the iPod portable media player (both developed, produced and marketed by Apple), although a slight earlier version. The iPad can run both dedicated applications, created especially for it, and iPhone applications. Like the iPhone and iPod, the iPad can only run applications approved by Apple itself and obtained through Apple's online AppStore.
The iPad uses Wi-Fi technology to browse the Internet, load or stream media, but Apple also released a model with 3G wireless connection. Even though the iPad is supposed to be a substitution for a computer, a PC is needed to manage and sync data on the device via iTunes and USB cable. The iPad uses Apple's multi touch sensitive screen. The iPad's screen is a 25 cm liquid crystal display which supports a 1024x768 resolution. Like in the case of the iPhone, the iPads's screen was designed to be used by bare finger ( some actions require multiple fingers, such as zooming out or in of a web page by executing a movement known as pinching which requires one to move two fingers in opposite directions ) so normal gloves and styluses will not work on the tablet because they are not able to produce a sufficient amount of electrical conductivity.
Even tough, there are special gloves and capacitive styluses that work. There are two other sensors that function in the iPad: The ambient light sensor which inspects and sets the best brightness at a specific moment, and the 3-axis accelerometer sensor which helps the iPad identify in what direction it is moved so the user can easily switch from portrait mode to landscape mode.
Different from the iPhone or iPod, the built-in applications of which support only three modes (landscape-left, landscape-right and portrait), the iPad's built-in application supports an additional upside-down mode, so basically the tablet has no native orientation, as the position of the home button being the one one which changes.
The device has a switch for rotation lock, which turns off the tablet's mode changing function (reportedly to prevent unintended rotations when the user is lying down). There are four physical buttons on the iPad: the rotation lock switch mentioned earlier, the awake/sleep button which (as its name suggests) puts the device on "sleep" and turns it back on, the volume keys and the Home button, which closes the current application and redirects the user to the home screen.