Syphilis is an STD caused by the bacteria Treponema pallidum. It's sometimes called the "great imitator" because early symptoms are so similar to other diseases. The disease proceeds through stages -- In primary syphilis, a chancre -- an open sore that's usually painless -- appears, most commonly on the genitals, usually 10-90 days after exposure. In secondary syphilis, a skin rash appears, on any part of the body, including palms of hands & soles of feet. In tertiary syphilis, the disease spreads to internal organs, where it can do serious damage. A pregnant woman can pass the disease on to her child. Having syphilis makes a person more susceptible to HIV. Early diagnosis is important because syphilis is readily treatable with antibiotics.
Picture from CDC/PHIL (see Syphilis Pictures), text paraphrased from several sources on list below.
