Excavator : construction

Aka Digger, (Tracked excavators are sometimes called trackhoes)

An excavator, also called a 360 degree excavator, sometimes abbreviated simply to a 360, is an engineering vehicle consisting of a backhoe and cab mounted on a pivot

A backhoe, also called a rear actor, back actor or JCB, is a piece of excavating equipment consisting of a digging bucket on the end of an articulated arm (also called a stick or dipper). Modern backhoes are powered by hydraulics. They are typically mounted on the back of a tractor or front loader.

Often the bucket can be replaced with other tools like a breaker, a grapple or an auger. Excavators are usually employed together with loaders and bulldozers. Most smaller excavators have a small backfill blade. This is a horizontal bulldozer like blade attached to the undercarriage and is used for pushing removed material back into a hole.

In recent years, hydraulic excavator capabilities have expanded away past excavation tasks. With the advent of hydraulic powered attachments such as breakers, clamps, augers (drill), and compacto

Often some are rubber tracked so they can travel on soft, muddy ground.
Usage

Brush cutting; Digging of trenches, holes, foundations; Demolition; General grading/landscaping; Heavy lift, e.g. lifting and placing of pipes;
Mining, especially, but not only open-pit mining; River dredging

Mini digger
The smaller ones are called a mini excavator or compact excavator. Can be as small as 1470 kg (3240 lb), with a some with a maximum bucket size of only 0.04 m³ and the width of its tracks can be adjusted to 90cm.

Compact hydraulic

excavator is somewhat unique from other construction equipment in that all movement and functions of the machine are accomplished through the transfer of hydraulic fluid. The compact excavator's work group and blade are activated by hydraulic fluid acting upon hydraulic cylinders. The excavator's slew and travel functions are also activated by hydraulic fluid powering hydraulic motors.