One time, sooner or a bit later, it becomes part of every teenager’s life.
For adults sex is usually associated with a firm relationship, for teenagers it is usually associated with the ‘first love’, experimenting, learning, and very often not associated with a stable relationship, but with ‘casual’ encounters.

We must always take care of contraception. There’s varied methods that not only protect us against an undesired child, but also against several sexual diseases that can be caused by any sexual contact (vaginal, oral or anal).
For a teenager it is very important to know about sexual diseases and their symptoms, and to ask for help if he/she thinks it is necessary or has any doubts or questions. Protection may be never forgotten.
Most choose condoms or pills, as these are very easy to use. But it’s not obligatory. You may choose anything, as long as you’re 100% protected.