Guichet: how do you stay in touch with your teen?

Adolescence is a delicate age, the passage between the world of children and that of adults. Sometimes this ''journey'' doesn't go smoothly. How do you maintain a relationship with your teenager? How can we support him or her during this troubled period? Is it normal for him or her to do as he or she pleases? Spends hours on social networks? Should you crack down? Maintain a dialogue? Set limits?