Strong: This is about the coffee extraction and brew ratio. Extraction is how we measure the amount of solubles that, during brewing, are removed from the coffee grinds and enter the water. While this sounds more like a science lesson than brewing coffee, it’s important to understand it because extraction also affects the coffee’s flavor.
For this reason, grind consistency is crucial. If your grinds are different sizes, some of them will be extracted more than others – meaning it’ll be nearly impossible to get the profile you want.
At the beginning of my journey into specialty coffee, I ground my coffee with a blade grinder. These typically result in an inconsistent grind size, and that was showed in the cup. I switched to a handheld burr grinder, which changed my home brewing game. And when I finally switched to an electric burr grinder, it made it even easier for me to learn more about grind size and extraction.
As for ratio, a common choice is 1:16, meaning 1 gram of coffee to 16 grams of water.
As Alex mentioned, turbulence also plays a key role in the extraction. Some people give their coffee a stir at this point in time, to ensure all the grinds are exposed to the water. Others take an opposing approach: they pay close attention to the rate of their pour so as to not disturb the grounds while adding water.