The lead up to the Super Bowl is the best time to buy a new TV. But with all of the features, flourishes and companies fudging their sets’ numbers, figuring out which TV to buy can be quite a challenge. After all, you don’t want to click that buy button or go into the store and not know the difference between a 4K, HDR LED TV with local dimming, and a 4K, HDR OLED TV, do you?

No, you don’t. So, here’s a quick refresher on some of the key terms and specs to look for when buying a new TV.

4K TVs

You’ve probably heard about this term at nauseam, but here it is. 4K, also known as ultra-high definition or UHD, simply refers to a television with a resolution, the total number of pixels along its horizontal and vertical axes, of 3,840 pixels x 2,160 pixels. It’s only worth getting a 4K TV, though, if you’re purchasing a set with a screen that’s 55 inches or larger, since you’re unlikely to notice the difference between a smaller 4K TV with a 1080p resolution screen.

HDR TVs

HDR TVs are essentially televisions with screens that offer high contrast ratios. That means there’s a greater difference between the darkest the image can appear and the brightest it can appear. HDR also brings along a wider color gamut, which means your TV is able to show a larger range of colors than standard sets. Between 4K and HDR, HDR easily offers the most noticeable improvement in terms of image quality.

LED TVs

These are TVs that use LEDs, or light-emitting diodes, for their backlighting rather than cold-cathode fluorescent lights, which are less power efficient. Chances are if you’re buying an LCD TV today, it will have LEDs.

Edge lighting and local dimming

These go hand-in-hand with LED TVs. See, LED-lit TVs usually use lines of LEDs on their top, bottom or sides as light sources. That’s where the term edge lighting comes from. Local dimming is the ability for a TV to dim its LEDs in parts of an image while lighting others up.

You’ll see this on your TV when you load Netflix (NFLX) for instance. If your set uses edge lighting on its top and bottom edges like mine does, the edges of the screen will look black, while the Netflix logo will be noticeably brighter, adding depth to the image.

The problem is, edge lighting also lights up areas that are meant to be dark, due to light bleed. Take that Netflix logo, for example. While the sides of the screen will look dark, the black areas close to the Netflix logo will be a kind of muted black.

Companies try to fix this by using either lining the top, bottom, and sides of their TVs with LEDs rather than the top and bottom or just the sides. It’s better than if a TV didn’t use local dimming at all, for sure, but it’s not perfect.