People send Christmas cards to express their love and goodwill during the holiday season. It's a tradition that dates back to the Victorian era when people would send handwritten letters and cards to friends and family. Today, Christmas cards are still a popular way to spread holiday cheer and show appreciation for loved ones. Some people also send Christmas cards as a way of thanking friends and family for their support throughout the year, or as a way of expressing their holiday wishes. It's a thoughtful gesture that can bring joy and warmth to the recipients.