棋子的生命线 | The lifeline of every stone
"气"是围棋中最基本、最重要的概念。简单来说，"气"就是棋子周围直接相邻的空交叉点。注意，这里说的"相邻"是指上、下、左、右四个方向，不包括对角线。
你可以把"气"想象成棋子的呼吸空间。就像人需要空气才能生存一样，棋子需要"气"才能留在棋盘上。如果一颗棋子（或一组棋子）的气被全部堵住了，它就会被"吃掉"——从棋盘上移除。
理解气的概念是学习围棋的关键一步。所有进阶的战术和策略——吃子、做活、连接、分断——都建立在对"气"的理解之上。
当一颗棋子放在棋盘中间时，它的上、下、左、右各有一个空的交叉点，所以有 4 口气。下图中的绿点表示这颗黑棋的气：
4 口气是单颗棋子能拥有的最多的气。中间的棋子在四个方向都有空间，是最安全的位置。这也是为什么中央的棋子相对较难被吃掉。
当棋子在棋盘的边上时，有一个方向被棋盘的边界挡住了。棋盘外面没有交叉点，所以那个方向没有气。结果就是边上的棋子只有 3 口气：
这颗黑棋在左边缘，左侧是棋盘边界，没有交叉点，所以只有上、右、下三个方向的气。边上的棋子比中间的棋子少一口气，因此更容易受到攻击。
角落的位置最为危险。棋子被两条边界限制，只有两个方向有空间：
这颗黑棋在左上角，只有右边和下边两口气。对方只需要两手棋就能把这两口气堵住，然后吃掉这颗棋子。
气的数量直接决定了棋子的安全程度。气越多，对方需要花越多手棋来围攻你；气越少，你的棋子就越危险。
当两颗或更多同色棋子相邻连在一起时，它们组成一个"棋组"（group）。棋组的气是所有成员周围空点的总和（不重复计算）。棋组要么一起活，要么一起死——你不能只吃掉其中一颗。
比如两颗相邻的黑棋在中间，它们共有 6 口气（每颗棋子贡献 3 口独立的气）。连接棋子不仅增加了总气数，还意味着对方需要更多手棋才能吃掉整个棋组。这就是为什么"连接"是围棋中最基本的战术之一。
Liberties are the single most fundamental concept in Go. Simply put, a liberty is an empty intersection directly adjacent to a stone -- up, down, left, or right. Diagonal points do NOT count as liberties.
Think of liberties as a stone's breathing space. Just as a person needs air to survive, a stone needs liberties to remain on the board. If a stone (or group of connected stones) loses all of its liberties, it is "captured" -- removed from the board entirely.
Understanding liberties is the key step in learning Go. Every advanced tactic and strategy -- capture, life and death, connection, cutting -- is built on the foundation of liberties.
When a stone is placed in the middle of the board, it has one empty intersection in each of the four directions: up, down, left, and right. That gives it 4 liberties. The green dots in the diagram below show this black stone's liberties:
Four liberties is the maximum for a single stone. A stone in the center has room in all four directions, making it the safest position on the board. This is one reason why center stones are relatively difficult to capture.
When a stone sits on the edge of the board, one direction is blocked by the board's boundary. Since there are no intersections beyond the board, that direction provides no liberty. The result is that an edge stone has only 3 liberties:
This black stone on the left edge has the board boundary to its left -- no intersection exists there. It only has liberties above, to the right, and below. Edge stones are more vulnerable than center stones because they start with one fewer liberty.
The corner is the most dangerous position for an isolated stone. Two sides are blocked by the board's boundary, leaving room in only two directions:
This black stone in the top-left corner has only two liberties: one to the right and one below. Your opponent needs just two moves to block both liberties and capture this stone.
The number of liberties directly determines how safe a stone or group is. More liberties means your opponent must spend more moves to surround you; fewer liberties means your stones are in greater danger.
When two or more stones of the same color are directly adjacent (horizontally or vertically), they form a "group." A group's liberties are the total unique empty points surrounding all its members. A group lives or dies as a whole -- you cannot capture just one stone out of a connected group.
For example, two adjacent black stones in the center share 6 liberties (each contributes 3 unique liberties). Connecting stones not only increases the total liberty count but also means your opponent needs significantly more moves to capture the entire group. This is precisely why "connection" is one of the most fundamental tactics in Go.