Herpes

Spread during VAGINAL, ANAL or ORAL sex and sometimes touching of genitals or mouth during viral shedding period (usually accompanied by sores)
Many people have no symptoms
Can develop flu-like feelings during outbreaks
Small, painful blister or blisters on the sex organs (HSV-2) or mouth (HSV-1). Itching or burning before the blisters appear; blisters last 1-3 weeks; blisters go away but you still have Herpes and the blisters can come back.
HSV-1 can transfer and turn into HSV-2 and vice versa
80% of Americans have HSV-1. Descriptors like “cold sores” and “heat blisters” are just PC names for oral herpes (HSV-1).
About 1 in 6 Americans have genital Herpes; 80% of those who have it don’t know it

You can give it to your sex partners
Herpes can not be cured; there are medications to help lessen the effects of an outbreak, reduce the number of outbreaks experienced and reduce the likelihood of infecting a partner
A mother can give it to her baby during childbirth

Avoid contact with herpes sores, this is when the virus is at its most contagious. Condoms and dental dams can help prevent spreading of Herpes but only if the sores are effectively covered by the latex.
By being in an exclusive relationship with one partner; limiting number of sex partners; and choosing a partner who has had no or fewer sex partners.