Why STDs are considered as self-invited diseases?

Explanation

Sexually Transmitted Diseases (STDs) can be considered self-invited discases because one could be free of these infections, by following the simple principles given below
(i) Avoid sex with unknown partners/multiple partners.
(ii) Always use condoms during coitus.
(iii) In case of doubt one should go to a qualified doctorfor early detection and get complete treatment if diagnosed with disease. If all the above said precautions are not strictly adopted by people, they are inviting STDs to infect them.