Computer-aided design (CAD) is the use of computer technology to aid in the design and especially the drafting (technical drawing and engineering drawing) of a part or product, including entire buildings. It is both a visual (or drawing) and symbol-based method of communication whose conventions are particular to a specific technical field.

Drafting can be done in two dimensions ("2D") and three dimensions ("3D"). Drafting is the integral communication of technical or engineering drawings and is the industrial arts sub-discipline that underlies all involved technical endeavors. In representing complex, three-dimensional objects in two-dimensional drawings, these objects have traditionally been represented by three projected views at right angles.

Current CAD software packages range from 2D vector-based drafting systems to 3D solid and surface modellers. Modern CAD packages can also frequently allow rotations in three dimensions, allowing viewing of a designed object from any desired angle, even from the inside looking out. Some CAD software is capable of dynamic mathematic modeling, in which case it may be marketed as CADD — computer-aided design and drafting.

CAD is used in the design of tools and machinery used in the manufacture of components, and in the drafting and design of all types of buildings, from small residential types (houses) to the largest commercial and industrial structures (hospitals and factories).

CAD is mainly used for detailed engineering of 3D models and/or 2D drawings of physical components, but it is also used throughout the engineering process from conceptual design and layout of products, through strength and dynamic analysis of assemblies to definition of manufacturing methods of components.

CAD has become an especially important technology within the scope of computer-aided technologies, with benefits such as lower product development costs and a greatly shortened design cycle. CAD enables designers to lay out and develop work on screen, print it out and save it for future editing, saving time on their drawings.

Capabilities

The capabilities of modern CAD systems include:

• Tribrid 1 modeling
• Wireframe geometry creation
• 3D parametric feature based modeling, Solid modelling
• Freeform surface modeling
• Automated design of assemblies, which are collections of parts and/or other assemblies
• Create engineering drawings from the solid models
• Reuse of design components

• Ease of modification of design of model and the production of multiple versions
• Automatic generation of standard components of the design
• Validation/verification of designs against specifications and design rules
• Simulation of designs without building a physical prototype
• Output of engineering documentation, such as manufacturing drawings, and Bills of Materials to reflect the BOM required to build the product
• Import/Export routines to exchange data with other software packages
• Output of design data directly to manufacturing facilities
• Output directly to a Rapid Prototyping or Rapid Manufacture Machine for industrial prototypes
• maintain libraries of parts and assemblies
• calculate mass properties of parts and assemblies
• aid visualization with shading, rotating, hidden line removal, etc.
• Bi-directional parametric association (modification of any feature is reflected in all information relying on that feature; drawings, mass properties, assemblies, etc.)
• kinematics, interference and clearance checking of assemblies
• sheet metal
• hose/cable routing
• electrical component packaging
• inclusion of programming code in a model to control and relate desired attributes of the model
• Programmable design studies and optimization
• Sophisticated visual analysis routines, for draft, curvature, curvature continuity.'''