Hydration

This is the amount of liquid (usually water) in relation to flour. A starter or dough using 1kg/2lb 4oz of flour and 700g/1lb 9oz of water would be 70% hydration (I find it much easier to be accurate using metric weights). The lower the percentage, the stiffer the dough (for a bagel or tin loaf, for example) and the higher the percentage, the slacker the dough (great for a ciabatta or crumpet). Very high-hydration doughs can be referred to as batters, though there is no set cut-off point between the two.