The Apple IIc, the fourth model in the Apple II series of personal computers, was Apple Computer’s first endeavor to produce a portable computer. The end result was a luggable 7.5 pound notebook-sized version of the Apple II that could easily be transported from place to place. The c in the name stood for compact, referring to the fact it was essentially a complete Apple II computer setup (minus display and power supply) squeezed into a small notebook sized housing.
In technology, especially computing (irrespective of platform), a product is said to be backward compatible when it is able to take the place of an older product, by interoperating with products that were designed for the older product.