back and begin forming their own threats. Basic shapes Certain basic shapes are fundamental to skillful Pente play. The most important are stretch twos, open trias, stretch trias, and open tesseras. Pair A pair is a group of two stones directly adjacent. Pairs are the basis of Pente's capture rules and the only pattern in standard Pente susceptible to capture. Pairs are therefore very weak and vulnerable formations. Beginners are often told outright to simply avoid forming them in a game if they can due to their vulnerabilities. They can however be used to great advantage by intermediate and advanced players due to their ability to threaten to form open trias and their use in advanced tactics such as the wedge formation. Stretch two A stretch two is a pattern with stones placed near each other with an empty space in between. Stretch Twos are an important skill to learn for beginners. They offer two main things for a player. They can threaten to form a line of three stones, an open tria, if unbound on either side by enemy stones, and they stop the player from forming a pair. A pair is vulnerable to capture by the opponent and therefore a liability to player that formed it. If the opponent places a stone adjacent to either side of the pair the defending player must now either sacrifice the pair to capture and play elsewhere, create a threat in another location that can't be ignored by the enemy, or to protect it by extending it immediately and lose initiative. Open tria An open tria is a line of three stones that are not bound on either side of the line by an opponent's stones. Open trias are powerful because they threaten to form an open tessera on the next turn if the opponent doesn't respond to block the tria. Open tesseras are the most powerful shape in Pente, short of the eponymous and winning "pente" pattern of five stones in a row. An open tria allows the player who placed them to create initiative for themselves because of how it forces the opponent to move to respond. The ability to form many open trias each turn forces the other player to respond and allows the placing player to form a powerful board presence with many options for attack, while the defending generally has to place stones in many locations all