How were trenches used during WWI?

The troops on both sides lived in the trenches they slept in them they ate and died in them . The trenches were also death traps they were often full of water and mud also rats and when the shells fell on to them there were body parts of all the dead . The trenches were an open grave, an open sewer where the poor men had no choice to be they suffered at the conditions that they lived in with their feet rotting with trench foot the cold stinking conditions it was hell on earth. When they went over the top the men were shot to ribbons, by the enemy when shells fell they churned up all the mud when the soldiers got stuck in the mud injured they even drowned in it the first world war was a war to end all wars but sadly it was not true.