Caterpillar, commonly called CAT, is the world's largest heavy equipment manufacturer headquartered in Peoria, Illinois. CAT was formed in 1925 with the merger of companies Holt and Best.
CAT is perhaps best known for their complete range of construction equipment and heavy machinery. They also manufacture diesel engines for truck, bus, locomotive, and other applications.
On June 12, 2008, CAT announced that they would exit the business of supplying engines to on-highway original equipment manufacturers (OEMs) with the next EPA emission standard in 2010. CAT cites as the reason for leaving the on-highway engine business, a decline in the market for independant engine manufactures as more OEMs are using proprietary engines.