Concept in the game of Go
Life and death (死活) is a fundamental concept in the game of Go, where the status of a specific group of stones is determined as either being "alive", where they may remain on the board indefinitely, or "dead", where the group will be "captured" and removed from the board. The basic idea can be summarized by:
A group must have a means to evade capture -- forever -- by having at least two liberties that can't be filled at the same time (by having at least two "eyes") to sustain itself.