As mentioned on the previous page, grain is a unique aspect of the game of golf, especially when courses use Bermuda grass for their greens. Essentially grain is the direction in which the grass grows, and if you have any green-thumb experience at all, that usually means it always grows towards the sun.
Whether you like it or not, the grain will affect your putt as it will always pull or push the ball in the direction it’s growing. For example, on a level surface, a putt will be slower into the grain and quicker with the grain. You can tell which way the grain is going by looking at the color of the grass (if it’s shiny, it’s going with you) or by noticing the grass around the cup. Typically the side of the cup where the grass is a little more broken and the edge appears slightly more damaged will indicate the side of the cup towards which the grain is growing.