Mechanical engineering is a diverse subject that derives its breadth from the need to design and manufacture everything from small individual parts and devices (e.g., microscale sensors and inkjet printer nozzles) to large systems (e.g., spacecraft and machine tools). The role of a mechanical engineer is to take a product from an idea to the marketplace. Mechanical engineering deals with anything that moves, including the human body, a very complex machine. Mechanical engineers learn about materials, solid and fluid mechanics, thermodynamics, heat transfer, control, instrumentation, design, and manufacturing to understand mechanical systems. Specialized mechanical engineering subjects include biomechanics, cartilage-tissue engineering, energy conversion, laser-assisted materials processing, combustion, MEMS, microfluidic devices, fracture mechanics, nanomechanics, mechanisms, micropower generation, tribology (friction and wear), and vibrations. Open Access raises practical and policy questions for scholars, publishers, funders, and policymakers alike, including what the return on investment is when paying an article processing fee to publish in an Open Access articles, or whether investments into institutional repositories should be made and whether self-archiving should be made mandatory, as contemplated by some funders.

Mechanical engineering is an engineering discipline that combines the principles of engineering with physics and mathematics to design, analyze, manufacture and maintain mechanical systems.  It is one of the oldest and widest engineering disciplines. The field of mechanical engineering requires an understanding of key areas, including mechanics, dynamics, thermodynamics, materials science, structural analysis and electricity. In addition to the base, mechanical engineers use tools such as computer-aided design (CAD), computer-aided manufacturing (CAM) and product lifecycle management to design and analyze manufacturing plants, industrial machinery and equipment, heating and cooling systems, and transportation systems. , aircraft, personal watercraft, robotics, medical devices, weapons and others. It is the branch of engineering that is the design, production and operation of machines