If you want to understand lumber grading like a pro, you need to learn to talk the talk. So here’s your cheat sheet—a little guide to the lingo.

Lumber is not all created equal. In fact, each individual board is inspected and graded by a certified agency. They inspect it for different factors, but two of the terms you’re going to hear most often when you’re discussing lumber are “knotty” and “clear”.

The clear grade is exactly what it sounds like—visually clean and free from defects. You will see only a few, if any, knots, streaks, or any other kind of visual imperfections in the board. Knotty grades allow more inclusions. That’s not necessarily a bad thing. Structurally speaking, knotty grades are still an excellent and durable choice—they just have a more casual, rustic appearance to them than clear lumber does. Obviously, clear is much more expensive lumber. Because of the price variance, most people choose knotty for fencing.

Within these varieties are grades such as “1 and better” or “2 and better.” “1” represents the very finest lumber. The “and better” part of the phrase means that when you buy a lot of “2 and better” boards, you’re guaranteed that nothing in the assortment you receive will be lower than a 2, and some if it is going to be better than a 2. Grade 1 is custom order only because of the price. Grade 2 has small knots and inclusions and is the most common material used. Grade 3 or “big box” stores lumber is builder grade with many knots and inclusions.