A bulldozer is a crawler (continuous tracked tractor) equipped with a substantial metal plate (known as a blade) used to push large quantities of soil, sand, rubble, or other such material during construction or conversion work and typically equipped at the rear with a claw-like device (known as a ripper) to loosen densely compacted materials.
Bulldozers can be found on a wide range of sites, mines and quarries, military bases, heavy industry factories, engineering projects and farms.
The term "bulldozer" correctly refers only to a tractor (usually tracked) fitted with a dozer blade.
A very small bulldozer is sometimes called a calfdozer: Google search for images.
Most often bulldozers are large and powerful tracked heavy equipment. The tracks give them excellent ground holding capability and mobility through very rough terrain. Wide tracks help distribute the bulldozer's weight over a large area (decreasing ground pressure), thus preventing it from sinking in sandy or muddy ground. Extra wide tracks are known as swamp tracks or LGP (low ground pressure) tracks. Bulldozers have transmission systems designed to take advantage of the track system and provide excellent tractive force.
Because of these attributes, bulldozers are often used in road building, construction, mining, forestry, land clearing, infrastructure development, and any other projects requiring highly mobile, powerful, and stable earth-moving equipment.