Sexually Transmitted Diseases (STD) are infections that are spread by having unprotected sex with someone who is already infected. People can catch some of these diseases through other types of contact, but most often it is because they do not use a condom during sexual intercourse.
Genital Herpes is caused by the Herpes Simplex Virus (HSV). HSV type 1 is the virus that often causes the pus-filled blisters on your lips and the surround area; this infection often stays in the mouth area, but there are cases that it spreads to genitals with oral sex during an infection. HSV type 2 is the infection that causes the blister outbreaks in the genital area.
It is most contagious during the outbreaks, often passed on by skin-to-skin contact any time before the scab heals. Although you can still spread it when you are not having an outbreak, so it is important to always use protection (condoms and dental dams) do not spread the virus.
Besides the blisters, HSV outbreaks tend to make the area itchy or burning, and sometimes pain. The first outbreak is the worst, as it often includes headache, fever and other aches. Genital Herpes come and go, so there is no schedule on which to predict when it will happen, although stress and low immune system often awakens the virus.
There is no cure for genital herpes. You can have a doctor diagnose you with the STD, and there are medications to prevent or lessen the amount of outbreaks, but the virus is with you for life. As for symptoms, you can decrease the discomfort with cotton clothes or warm baths.
Of course, the best way to prevent Genital Herpes is to not have sex, or to use protection when you have a new partner (until tested and monogamous) and/or when you have multiple partners. And be sure to get tested regularly.