有超過40種能夠通過性接觸傳播的疾病，但是通常的教科書和統計中只包括最常見的種類。所以，性傳播疾病的病名錄可以隨時發生改變，以及依據其流行程度會作出調整。本課程包括了當今最重要的性傳播疾病，但是能夠按照情況的需要很容易進行增減。

通常，性傳播疾病被分為兩類——病毒感染類和細菌感染類。另外，還有一類由陰虱和蟎蟲引起的原生動物和害蟲類。後一類和細菌感染類性傳播疾病是當今能治癒的。但是，病毒類的性傳播疾病仍是不能治癒的，因而是一類需要特別做出預防努力的疾病。為了突出重點，我們在此將討論分成能治癒與不能治癒性傳播疾病。下面第一節討論能治癒性傳播疾病。這些疾病在許多國家仍然是一個主要的健康問題。

全球發生率（單位：百萬）1995年可治癒性傳播疾病新病例為3.33億
Global Incidence of Curable STDs in millions   333 million new cases of curable STDs in 1995, ages 15-49

There are over 40 diseases that can be transmitted through sexual contact, but only the most common ones are included in the usual textbooks and statistics. Thus, lists of STDs may change over time and include more or fewer diseases depending on their prevalence. The present course covers the most important STDs today, but it can easily be amended as circumstances require.
The STDs are usually divided into two major groups - viral and bacterial infections. In addition, there are infections by protozoa and infestations of pubic lice and scabies. The latter and the bacterial infections are curable today. The viral infections, however, are not yet curable and therefore require special prevention efforts. In order to underline this point, we have here divided our discussion into that of curable and incurable diseases. The following first section describes the curable STDs. They remain a major health problem in many countries.