Hydraulic excavators are powerful construction machines used for digging, lifting, and moving materials. They consist of a boom, arm, bucket, and a rotating platform, allowing them to perform various tasks on job sites. The hydraulic system enables precise control of the machine's movements, making it efficient for tasks like trenching, demolition, and material handling. These excavators come in different sizes and types, including mini excavators for smaller projects and larger models for heavy-duty work. They are commonly used in construction, mining, and landscaping, showcasing their versatility and importance in modern engineering and construction practices.