A "Brother-In-Law" is the term used to describe the brother of one's spouse or the husband of one's sibling. This relationship is part of the extended family and can vary in closeness depending on family dynamics. In many cultures, a brother-in-law can play a significant role in family gatherings and celebrations. He may also be involved in family decisions and support, similar to other family members. The relationship can be friendly, supportive, or, in some cases, distant, depending on individual circumstances and interactions.