The graphic cards play important role for gamers, graphic designers and 3D animators who tend to require optimum displays for their work as well as faster rendering in order to efficiently tone up their work whereas integrated or onboard graphics were capable of handling most day-to-day work and supports basic usage to run windows and it's features.
The concept of onboard graphics really came up when Intel integrated graphics with its 810-chipset based motherboards for the PIII processor. Intel didn't leave an option for putting in an additional graphics card, forcing people to use only onboard graphics, which eliminated a lot of graphics cards from the market. Intel later came up with the provision to add graphics cards as well, and this changed the face of the graphics market.People didn't feel the need to buy a separate graphics card, because the onboard card served the purpose well. Intel brought iterations of its onboard graphics, with the latest one being the Extreme Graphics 2 core for the P4 processor. Along the way, two major graphics manufacturers joined the race by introducing their motherboard chipsets with onboard graphics. These were NVIDIA with its Nforce and Nforce 2 chipsets, and ATI with its latest Radeon 9100 IGP (Integrated Graphics Port). So today, with graphics manufacturers in the race, onboard graphics have become quite powerful. You can play games, watch movies, or run high-end graphics applications. That brings us to the million-dollar question of why go for a separate graphics card.