In Britain, Boxing Day is usually celebrated on December 26th , which is the following day after Christmas Day . However , strictly speaking, Boxing Day is the first weekday after Christmas . Like Christmas Day, Boxing Day sings a public holiday . This means it's a non - working day in the whole of Britain . When Boxing Day falls on a Saturday or Sunday , the following Monday is the public holiday . The exact origin (起源) of the holiday is unclear . One of the thoughts is that during the Middle Ages , when great sailing ships were setting off to discover new land , a Christmas Box was placed by a priest( 神父 )on each ship . Those sailors who wanted to ensure a safe return would drop money into the box . It was sealed up and kept on board until the ship came home safely . Then the box was handed over to the priest in the exchange for the saying of a Mass of thanks for the success of the sailing . The priest wouldn't open it to share the contents with the poor until Christmas . One more thought is about the “ Alms Box ” placed in every church on Christmas Day . Worshippers (做礼拜的人) put gifts for the poor into it . These boxes were always opened the day after Christmas , that is why that day became known as Boxing Day . Today , many businesses , organizations and families try to keep the traditional spirit of Boxing Day alive by donating (捐赠) their time , services and money to aid Food Banks , providing gifts for the poor , or helping families in need . Besides , spending time with family and shopping are popular Boxing Day activities now .