Aslef stands for the Associated Society of Locomotive Engineers and Firemen, a trade union in the United Kingdom. Founded in 1880, it represents train drivers and other railway workers, advocating for their rights and working conditions. The union plays a crucial role in negotiating pay, safety standards, and job security for its members. Aslef is known for its strong stance on issues affecting the railway industry, including safety regulations and the impact of automation. The union also engages in political activities to influence legislation that affects its members and the broader transport sector.