Think back to when you first heard the term sexually transmitted disease (STD).

Middle school, right? Probably in a classroom where giggles and darting eyes abounded, sandwiched between information on where babies come from and the lowdown on your period.

But fast-forward a few years (to, like, now) and all of a sudden everyone is calling them STIs (a.k.a. sexually transmitted infections). Now your middle school self is all confused.

What’s an STI—and how is it different than an STD (if it is at all)? Don’t freak, you’re not alone in your confusion.

Basically, STDs and STIs are the same things.

Or at least, they represent the same group of viruses and conditions—syphilis, gonorrhea, chlamydia, you know the drill.

The major difference in terminology, however, is that one is symptomatic (STD) while the other (STI) is not, says Angela Jones, M.D., an ob-gyn at Healthy Woman Obstetrics and Gynecology in Monmouth, NJ.

“You can have an infection, such as chlamydia, without symptoms,” Jones says. “Disease simply means that symptoms of said ailment are present and we only describe things as diseases when symptoms are present.”

That’s where the the choice to use STI comes into play, Jones explains—because many infections acquired sexually can be asymptomatic (e.g. herpes).

Teena Chopra, the corporate medical director of infection prevention and hospital epidemiology at Detroit Medical Center and Wayne State University, agrees, adding that “the term STI can be used in persons infected with sexually transmitted pathogen whether they develop symptoms or not.”

“[It] is a much broader and encompassing term than STD,” says Chopra. “It is likely that STI came into usage to incorporate certain infections—such as herpes virus or human papilloma virus (HPV)—where a large proportion of infected persons do not develop symptoms for many months to years or do not develop symptoms at all.”

Another reason why STI has become more mainstream than STD: the stigma attached to the term STD because of the word “disease.”

“Somehow, infection seems to be a bit more ‘palatable,’” she says. “Medically speaking, in my realm of obstetrics and gynecology, we tend to lean more toward the term STI.”

Basically, using STI instead of STD might take some of the stigma away—which might even help people feel more comfortable seeking medical help.

The bottom line: STDs and STIs are basically the same things—but STI means the infection doesn’t show symptoms.