Graphic EQs look like the multiband EQs on your dad's old hi-fi, with faders boosting and cutting frequency bands and, ironically, are not as graphic as parametric EQs (see below). They have a simple design and are often modelled on classic hardware. The frequency ranges the bands cover are fixed, but the number of bands can increase up to around 30, so as they increase so the bandwidth of each decreases, allowing for more precise EQing.
The shape of the faders matches the frequency response curve so it's easy to see what you are doing, and the simplistic design means there's not a great deal that can go wrong. They deliver a natural sound and are good for getting into a mix and quickly shaping your tone.
Parametric EQs are the most common EQs - indeed, most of the EQs we cover above are parametric. They enable you to control the frequency, amplitude and width of your EQ action graphically and can be very precise. They usually have attractive visual spectrum displays showing the whole frequency range from left to right. You select a number of bands as points on the screen - from half a dozen upwards - and click and drag the bands to adjust the amount of the centre frequency up and down.
You can adjust the Q - the width and slope of the frequency range applied. A high Q results in a narrow and dramatic EQ boost or cut, and these are great for making surgical cuts and boosts. You can also apply different filter shapes to each, so low-pass, notch, high-pass and so on. They tend to be clean and precise but don't tend to add colouration or character to a signal.