Please describe the medication: azithromycin?

Antibiotic: Treats infections caused by certain bacteria. This medicine is a macrolide antibiotic.

Azithromycin: Azithromycin (zithromax, azithrocin, zmax, azin)[1] is an azalide, a subclass of macrolide antibiotics. Azithromycin is one of the world's best-selling antibiotics.[2][not in citation given (see discussion.)] it is derived from erythromycin, with a methyl-substituted nitrogen atom incorporated into the lactone ring, thus making the lactone ring 15-membered.