Go Opening Principles: Corners, Then Sides, Then Centre

Why play the corners first

There is a clear reason for taking the corners first in Go. Territory is made by surrounding empty points with stones, and in a corner two edges of the board already act as walls, so you need fewer stones to build territory there. On a side you can use only one edge, and in the middle of the board you have to wall off every direction yourself. In other words, the number of stones needed for the same amount of territory grows from corner to side to centre. An old Go saying holds that corners are worth the most and the centre the least, which is exactly this difference in efficiency. That is why most games begin with the players sharing out the four corners.

First moves in a corner

A few corner moves are typical. The point where the fourth lines from two edges meet is called the 4-4 point (hoshi), the point where the third and fourth lines meet is the 3-4 point, and the point where the third lines meet is the 3-3 point. The 4-4 point claims the corner roughly in one move and spreads outward quickly, but an invasion at 3-3 can take the corner territory away. The 3-4 point protects the corner more firmly but needs one more move to secure it. The 3-3 point takes the corner territory with certainty but has less outward influence. Think of them as having different characters rather than one being correct.

• 4-4 point: fast and wide, but the corner is thin
• 3-4 point: solid corner, one more move to secure
• 3-3 point: secure corner, weak outside influence

The third line and the fourth line

Which line you play on along a side is at the heart of opening judgement. The first and second lines are too low: even with many stones you gain little territory. The fifth line and above are too high, leaving room for your opponent to slip underneath. So opening stones are usually placed on the third and fourth lines. The third line is good for turning the area below it into secure territory, while the fourth line gives less certain territory but more influence towards the centre. Stick only to the third line and you may have territory but fall behind on the board as a whole; stick only to the fourth and your framework may look wide while real territory falls short, so balance matters.

After the corners, the sides

Once stones sit in all four corners, play continues with an enclosure, an extra move that secures your corner; an approach, a move towards your opponent's corner stone that stops it enclosing on its own; and an extension, a stone placed along the side at some distance from the corner. Spacing matters with extensions. Too close and the area you claim is small and inefficient; too far and your opponent can play in between and split your stones. A reasonably safe rule of thumb at first is to extend two or three points along the third line, adjusting for where your opponent's stones are and how strong your own are. Only once the big points on the sides are mostly settled does the fight in the centre begin in earnest.

Urgent points before big points

The most common opening mistake is to look only at the largest empty area on the board. Taking big points matters, but first you should check whether any of your stones are in immediate danger. If you leave a weak group without enough room for two eyes and play a big point instead, your opponent attacks that weak group and gains even more. Conversely, when you attack your opponent's weak group, territory and influence naturally form on your side while it runs. Remember the order: look after your own weak groups first, attack your opponent's weak groups next, and then look for the biggest point.

Understand joseki rather than memorise it

Joseki are sequences in the corner in which both sides play what are considered the best moves. Learning joseki reduces big losses in the corners, but if you only memorise the moves you will not know what to do when your opponent deviates, and you may choose a joseki that does not suit the surrounding stones and lose out. When studying joseki, check what each move protects and what it aims at, and who gained territory and who gained outside influence once the sequence ends. Understanding that the best choice for the same corner depends on the stones in the neighbouring corners matters far more than the number of sequences you can recite.

Common opening mistakes

The mistakes beginners make in the opening tend to repeat. When you review your games, check whether any of these appear often.

• Playing on in one corner and giving up all the others
• Chasing captures and missing big points
• Crawling along the first or second line for tiny territory
• Leaving a weak group to play elsewhere
• Starting in the centre and making territory hard to build

The habit of seeing the whole board

To apply opening principles in real games you need the habit of scanning the whole board before each move. Ask in turn what your opponent's last move is aiming at, where the large empty areas still are, and which groups, yours or your opponent's, are weak. Practise these questions on a 9 by 9 board first, then widen to 13 by 13 and 19 by 19 as you get comfortable. Keep in mind that on a 9 by 9 board the corners and sides are so close together that the opening quickly turns into fighting, so your feel for the 9 by 9 opening does not carry over directly to the full board.