Your fertility is your ability to conceive a baby through unprotected sex: infertility is when this becomes difficult. In most cases, it's not as straightforward as being either fertile or infertile - many factors can decrease, but not completely eliminate, your chances of having a baby.
This is a companion discussion topic for the original article at https://patient.info/news-and-features/how-common-is-male-infertility-and-what-causes-it