A GPU or Graphics Processing Unit is a dedicated processor often used to handle accelerating the renderings of images, video, and 2D or 3D animations. As newer technologies are being developed, the GPU is being utilized to handle data for deep learning, allowing for things like cancer strand research, AI, autonomous driving, speech and face recognition.
There are two main forms that a GPU can take. One is a discrete physical add-on card for a PC, most commonly referred to as a Graphics Card, that you can buy and plug into your computer via a PCI Express slot. Another is an Integrated Graphics Processor (IGP) or Accelerated Processing Unit (APU). An IGP can be found integrated into a CPU or attached directly to a motherboard.
A dedicated graphics card offers far more performance then an IGP. It has a CPU with many more specialized cores to process the data, faster ram, and even power, leaving more room for the CPU and system to process additional tasks. Because it is a physical card, you are able to upgrade this part if you need more performance. With an IGP it shares all of its resources directly with the CPU and the system, hitting its max performance limits much faster.
There are two main GPU companies for PCs, AMD and NVIDIA, with possibly Intel getting in on the discrete card game in the near future. NVIDIA currently offers the best performing high end GPUs on the market and was first to feature real-time ray tracing. AMDs offerings are geared towards the mainstream 1080p scene with great performance for the price. Both may be showing off new hardware by this holiday or at least the beginning of next year.
How do you choose the right GPU for you? A good place to start researching is going to be the software you use the most. Many companies will have a list of minimum or recommended specifications, which will tell you exactly what is needed. I would suggest looking at their recommended specs, upgrading or downgrading from there, depending on your budget. Another great tool for games would be SystemRequirementsLab.com. It can scan your current hardware and compare game specifications for you.
Check out AMD and NVIDIA GPUs here: