Integrated graphics cards are typically soldered directly to the motherboard, so users can't remove them without specialized tools. Furthermore, removing an integrated chip can cause the motherboard to fail. However, a person can connect a discrete graphics card to the computer, which lets her bypass the integrated chip.
An integrated graphics card shares RAM with the CPU, and some of them provide basic 3D acceleration and video playback. This integration can save power and space, but the chips rarely provide the performance of even entry-level dedicated graphics cards. By attaching a graphics card, a person can take advantage of its superior performance and leave the computer's main RAM for the CPU.