Christmas. A family gathered around the Christmas tree, showing how much they love each other, through the presents they give. Or a ruthless battle for relationship control. In Christmas-celebrating nations, millions of pounds a year are spent on corporate Christmas gifts. Companies want to strengthen the relationship they have with other businesses or with customers, and gifts create a feeling of obligation, which ties them together for the rest of the year. Corporate giving is also a form of 'impression management', where organizations try to control the image clients and business partners have of them, through their choice of gift. Giving presents is also about showing you care, and that you know and understand someone. That's true in the home, which is one reason why choosing the perfect gift is so hard. And it's true in business as well. Companies use their corporate Christmas gifts to show they value their relationship with customers and partners. But it's not all good. Gift giving can also make us feel insecure or cause bad feeling. Will we give too little, and receive something better in return? That could make us embarrassed or ashamed. Or will we give too much, and make the receiver of our gifts feel bad? Sociologists and anthropologists have studied gift exchange for many years. Marcel Mauss was a famous sociologist, who, in the 1920s, studied a type of gift-giving festival among indigenous people in North America, called a potlatch. He found that the people at a potlatch try to 'outgive' each other, with more and more lavish presents, until eventually some people can't compete and give up. They lose face, and are left feeling subordinated to the gift-giver who 'won' the exchange. At home and in business, the effects of the presents we choose this Christmas will last the whole year round.