In males who have been circumcised, the circumcision scar refers to the scar

Scar

Scars are areas of fibrous tissue that replace normal skin after injury. A scar results from the biological process of wound repair in the skin and other tissues of the body. Thus, scarring is a natural part of the healing process. With the exception of very minor lesions, every wound results in...

 after a circumcision

Circumcision

Male circumcision is the surgical removal of some or all of the foreskin from the penis. The word "circumcision" comes from Latin and ....

 has healed. In some cases, the scar can be darker-colored, and, in all cases, it will encircle the shaft of the penis

Penis

The penis is a biological feature of male animals including both vertebrates and invertebrates...

.
The scar is located at the boundary of the outer foreskin and the inner foreskin

Foreskin

In male human anatomy, the foreskin is a generally retractable double-layered fold of skin and mucous membrane that covers the glans penis and protects the urinary meatus when the penis is not erect...

 remnant, which is the portion of the foreskin that was not removed during circumcision. This foreskin remnant is mucosa that lies between the glans and the circumcision scar, which results in dissimilar tissue healing together.