Apple Pencil is a stylus for the iPad Pro. Integrating with Apple's Multi-Touch capabilities, the stylus allows users to draw, write and tap icons by pinpointing down to a single pixel on the touchscreen.
Apple Pencil works with a variety of native iOS apps such as Mail and Notes, and third-party developers can support it in their apps as well. Sensors in the stylus' tip detect the pressure at which users touch the screen, allowing them to create thicker or thinner lines. The stylus also detects the angle at which users hold it, to create a shading effect that makes drawn objects appear more three-dimensional.
There is nearly no latency between when Apple Pencil touches the screen and when the corresponding action occurs, according to Apple. The interaction is very responsive because the Pencil receives twice as many data points from the screen as it would with a user's finger -- making the display occur faster. The iPad Pro also includes a palm rejection feature that senses when the stylus is in use and ignores any other touches by the user's hand that may occur on the screen at the same time.
The Apple Pencil has up to 12 hours of battery life. Users can charge it by attaching it to the iPad Pro via the Lightning connector under its magnetic cap. Apple Pencil is sold separately from the iPad Pro and as of this writing, costs $99.