When referring to a child, custody means the person who makes decisions for the child and with whom the child resides. When parents separate, decisions must be made about where the child will reside and how major, non-emergency decisions (such as where the child will attend school, his religious upbringing, etc.) will be made. In a perfect world, the parents will agree upon custody of their child. However, if they disagree, the court must decide.
The court may award sole custody to one parent or the other parent. This is more likely to happen in cases where the parents disagree frequently and strongly. The parent with sole custody makes all the major, non-emergency decisions for the child and the child resides with that parent. The other parent usually parenting time (visitation in some states) with the child and will still make minor decisions, such as bedtimes when the child is with him or her, and emergency medical decisions, such as when to call 911 if an emergency arises when the child is with him. In cases of abuse or neglect, however, the other parent may have supervised visitation or no visitation.