Gyeo-roo-gi (sparring) is the way that Taekwondo students prepare for self-defence.
In Songahm Taekwondo, a student first learns a form of preparatory moves known as 1-step sparring. This exchange of techniques is under strict control, and by memorizing these moves the student needs only practice distance and timing without the fear of responding to spontaneous techniques from an opponent. In this way, the basics of sparring can be safely developed before the student's reflexes are challenged. 1-steps also help a student acquire the confidence they need for sparring with a real opponent.
Later in their training, a Songahm Taekwondo practitioner begins applying the basics they have learned from 1-steps into true sparring, which can be thought of as reflexive responses against an unplanned attack. Essentially, they learn to move beyond the predetermined series of movements they have relied upon in favour of spontaneous movements designed for true self defence.
Although we learn sparring as a form of self defence, it is also very important in Songahm Taekwondo for other reasons. It helps display proficiency in techniques, and for this reason at the Camo Belt level and beyond sparring is evaluated for purposes of advancing to the next rank. It is also an important part of tournaments, where students can display their abilities in a safe, controlled competitive environment while still showing respect to their opponent.