Tara first appears in season four, when she attends the same wicca group as Willow. She immediately senses her power and the two start chatting.
Having quite a high knowledge of magic and very much in touch with her wicca side, Tara shows Willow several spells.
As the two spend more and more time together, Willow keeps her in the quite and doesn't talk to her to the gang, although Tara knows all about them and the slaying. Their relationship grows to be rather ambiguous and Faith (in Buffy's body) is the first to realise they're in love. Willow tells a surprised Buffy a little later, but Xander and Giles don't know until the very end of the season. Tara remains a bit of an outcast amongst the gang, not sharing the same tastes or humor, but she is definitely one of theirs, Buffy proves it when Tara's family try to force her home. He sweet and soft personality are quite a change in the gang and Dawn becomes particularly attached to her.
Tara is worried about Willow's abuse of magic and eventually leaves her when she uses magic on her, feeling betrayed. As Willow manages to quit magic, they get back together. As they make the most of their reunion, Tara is hit by a lost bullet as Warren tries to kill Buffy, and falls in Willow's arms, dead.