While these guidelines are general ones, you are an individual. Your healthcare provider may have different recommendations based on your individual health status and history, of course.
Who should get tested for:
STDs/STIs in general
CDC guidelines don't suggest routine STD/STI testing if you don't have any symptoms. However, CDC does recommend routine testing for men who have sex with men. If you are entering a new relationship and are interested in general testing, know that not all doctors perform the same tests for STD/STIs. Learn which tests you need and which you might have to ask for.
Chlamydia
CDC recommends yearly chlamydia testing of all sexually active women age 25 or younger, as well as older women with risk factors for chlamydial infections (those who have a new sex partner or multiple sex partners), and all pregnant women. Men should speak with their healthcare provider if they are at risk for chlamydia and if testing is recommended. Testing is a simple as peeing in a cup.
HIV
The CDC recommends at least one HIV test for everyone aged 13 to 64 who visits a doctor. Most HIV is transmitted by the 25% of infected people who do not realize they are infected.
Cervical cancer
Pap tests, as a cervical cancer screening tool, are recommend for women at either age 21, or within three years of the first time you have sex--whichever comes first.
Breast cancer
CDC recommends mammograms for women every one or two years starting at age 40.
Or another way to look at screening is . . .
What testing is recommended for . . .?
Women age 25 or younger
CDC recommends yearly chlamydia testing of all sexually active women age 25 or younger.
Women age 21 and older
Pap tests (to screen for cervical cancer) are recommended for women at age 21, or within three years of the first time a woman has sex—whichever comes first.
Men who have sex with men
Men who have sex with men should talk to their healthcare providers about general STD/STI screening.
Everyone age 13 to 64
The CDC recommends at least one HIV test for everyone aged 13 to 64 who visits a doctor. Most HIV is transmitted by the 25% of infected people who do not realize they are infected.