What is the trench warfare? And what problems were there with it?

Diseases such as trench fever (an infection caused by louse faeces), trench nephritis (an inflammation of the kidneys), and trench foot. On the Western Front, the war was fought by soldiers in trenches. Trenches were long, narrow ditches dug into the ground where soldiers lived. They were very muddy, uncomfortable and the toilets overflowed. These conditions caused some soldiers to develop medical problems such as trench foot.