Summer was previously a student of Beacon. She graduated from the school with Team STRQ.
Summer was the leader of Team STRQ.
Ruby is Summer's daughter. Ruby states that her parents taught her to always help others, presumably referring to Summer and Taiyang. According to Yang, Ruby was also devastated by the loss of Summer, but she may have been too young at the time to fully grasp the situation.
Ruby still routinely visits Summer's Gravestone, doing so in the "Red" Trailer, "Round One", and in "End of the Beginning". Ruby apparently finds solace in speaking to her mother, updating her on the events of her life and her feelings, and evidently lamenting her absence.
Summer was Yang's stepmother, and until after her death, Yang was evidently unaware of the fact Summer was not her biological mother. Yang spoke highly of Summer, referring to her as a sort of "super-mom" for herself and Ruby.
Following the disappearance of Raven Branwen, Summer entered into a relationship with Taiyang that resulted in a child - Ruby. She also acted as a mother figure for Yang. It is not clear if the two were married. After Summer's death, Yang said that Taiyang "shut down", devastated by the loss, implying that he and Summer were extremely close.
It is unclear what relationship the two had between each other, but both were teammates along with Qrow and Taiyang.
Qrow was Summer's teammate. Not much is known about their relationship. In "Family".