What is the touchline in soccer?
The touchlines are the long lines on each side of a soccer pitch. When the ball completely crosses the touchline, either from a deflection or errant pass, the team that did not last touch the ball is awarded a throw-in to restart play. For this reason, the area just outside the touchline should remain clear of any equipment, signs or other players, because it can see a lot of action.
It is primarily the job of the assistant referee to monitor the sightline along the touchline and raise their flag to signal that the ball is out-of-bounds.
The touchlines are also known as sidelines and they form the field of play with the end lines. The lines themselves are considered inbounds, but beyond these lines is out of bounds. It also includes the area on the pitch beyond these lines where the manager, staff, and players are allowed to be during the match.