American Sexual Health Association (ASHA, the sponsor of this forum):  https://www.ashasexualhealth.org/stds_a_to_z/ 

CDC:  https://www.cdc.gov/std/general/default.htm

WHO:  https://www.who.int/news-room/fact-sheets/detail/sexually-transmitted-infections-(stis)

FYI:  Don't get concerned or hung up on STD versus STI. Although some sources prefer one term over the other, in fact it's just a matter of personal preference. There is no difference in meaning. (And English is the only language for which there is any debate. In all other languates, there is only one term in use.)

One of the potential problems is terminology:  Lots of bacteria and viruses are sexually transmissible but usually not sexually transmitted. COVID-19, influenza, tuberculosis, staph, strep, and many others all can be shared by partners during sex, but since sex accounts for few cases (and if sex didn't exist it wouldn't make any difference in their frequency), they aren't considered STDs. Some conditions are sexually transmitted in some populations, but not others. Among men who have sex with men, many intestinal infections are almost always sexually transmitted, but sex is a rare cause in heterosexuals. Hepatitis C virus is often listed as an STD, but the only sexual transmission scenario that occurs with any measurable frequency is between men having traumatic (i.e. potentially bloody) sexual practices with other men; it is not sexually trnasmitted at all between men and women, or so rarely the risk can be ignored.

Please be cautious about "getting tested for as many STIs/STDs as possible". As one common example, the blood tests for HSV1 and HSV2 are not very good; in people without symptoms they so often are wrong or misleading that experts recommend against testing except in high risk circumstances, like symptoms that suggest herpes or sexual exposure to a known infected partner. By the same token, some tests included in some laboratories "comprehensive" STD testing panels are entirely unnecessary and included as much for the lab's profit motive as anything else. For example, even though EBV, CMV and HTLV [you can look them up if unfamiliar] can be STIs in some settings, they usually are not and positive results usually don't matter. Such panels also often include sexually transmissible bacteria like Ureaplasma urealyticum and Mycoplasma hominis which in fact are entirely normal bacteria in the genital tract and do not need treatment even if positive. For other STDs, there is no lab test anyway (e.g. molluscum contagiosum). On top of all this, there are syndromes whose exact cause is unknown:  for example, with current technologies the causes in 50% of cases are unknown and (so far) unknowable for nongonococcal urethritiis (NGU) in men; and it's more like 60-70% in its female counterpart, nongonococcal cervicitis. Then there's bacterial vaginosis, the most common cause of abnormal vaginal discharge in women -- whose cause is unknown and many cases of which may or may not be STDs at all.

As a general rule, the average sexually active person who changes partners from time to time should be tested periodically for gonorrhea, chlamydia, HIV and syphilis; and for women, perhaps trichomonas. And that's usually just about all.

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD