Resistant Body: A body is called resistant body if this is capable of transmitting the needed forces with negligible deformation.

Machine: A machine is a mechanism or a set of mechanisms that transmits force through the source of power to the resistance to be overcome, and therefore performs useful mechanical work. Mechanism plays the vital role of converting one type of motion into another.

Mechanism: A mechanism is a combination of restraining or rigid bodies therefore shaped and associated that they move upon each other along definite relative motion. Slider-crank mechanism utilized in internal combustion engine or reciprocating air compressor is the easiest example.

Rectilinear Translation: This is simplest kinds of motion and is along a straight line path.

Curvilinear Motion: This is the motion along a curved path. Such a motion is restrained to either one plane or space.