Gonorrhoea (gonorrhea in American English, slang term "the clap") is among the most common curable sexually transmitted diseases in the world and is caused by the Gram-negative bacterium called Neisseria gonorrhoeae.

Infection with gonorrhoea increases the risk of becoming infected with HIV (human immunodeficiency virus, the virus that causes AIDS). This is likely due to weakening of the mucosal surface secondary to the gonorrhoea infection. Note, however, that this effect is by no means limited to gonorrhoea and there is increased risk of HIV transmission with co-infection of most sexually transmitted infections (STIs - Sexually Transmitted Infections).

The first place this bacterium infects is usually the columnar epithelium of the urethra and endocervix. Non-genital sites in which it thrives are the rectum, the oropharynx and the conjunctivae (eyes). The vulva and vagina in women are usually spared because they are lined by stratified epithelial cells -- in women the cervix is the usual first site of infection.