Why did trench warfare lead to a stalemate on the western front

Trench warfare involved both sides occupying trenches dug into the ground.  In order to advance, soldiers had to climb out of the trenches and charge at their enemies, who were entrenched.  Since the ground often provided little to no cover, soldiers who attempted to advance would be brutally killed, as those who were defending their trenches could easily rip apart targets.  Consequently, it became understood that charging between trenches was close to suicide, and so little troop movements were made overall, leading to a stalemate.