Safe sex, or more accurately known as safer sex, is taking an active step in the prevention of transmission of STIs and STDs. Some forms of safe sex are also preventatives for pregnancy.
Much of the BDSM community was destroyed during the 1970's and 1980's due to STIs. Do not become another statistic. Understand that there is no form of sexual encounter with a partner that is risk free.
Empower and educate yourself to understand the risks of what types of activities you engage in as the consequences of not knowing can be life altering or life ending. Head here for more information on safer sex.