Memory or Random Access Memory (RAM) allows your computer to multitask. It temporarily stores data and the higher number of GB (Gigabytes) means more applications can be running in tandem without slowdowns. Some intensive applications for gaming or video editing, require more RAM for optimal performance.
Memory described as 'DDR' stands for 'Double Data Rate' and processes data approximately twice as fast as a standard memory module. When a number appears after DDR (ie DDR3) that type of memory is approximately twice as fast as the previous generation.

The graphics card (or video card or GPU) displays everything you see and are an essential piece of hardware. It determines the range of color, how sharp images appear, and how well videos or games run without stuttering or pausing. Integrated graphics are built-in to your PC's processor, while dedicated or discrete graphics are separate from the processor and enable you to run smoothly more advanced programs although they typically use more power.