AutoCad is one of the most famous computer programs for computer designing and drafting. The author of the program is the company Autodesk which offers over 75 specialized software tools and aids for different expert fields (mechanical engineering, electrics, electronics, civil engineering, architecture, cartography, geodesy, etc.). The basic program – AutoCad – is a sophisticated, designing tool of wide, you could say universal, purpose which supports two-dimensional designing, which basically replaces classic designing on paper, i.e. drawing board, divider, ruler, and three-dimensional modeling of complex objects which, in model space, can be zoomed in, bent over, turned, shown in different projections, angles and cross sections from all directions, with perspective effect or without it, illuminate at will and render it, so that the 3D display imitates the photography of a virtual object which exists only in the computer memory. Unlike the alternative software products for 2D and 3D modeling, AutoCad is specific for its sophisticated (perhaps even too complicated) system of sizing and high precision which can go under milimicrons and a system of setting dimensions and measurements with automatic calculations satisfying even the highest technical standards. With certain conditions, setting dimensions is associative, i.e. it automatically adjusts to the changes in geometry of the processed model.

2D – Two dimensional regime
In the regime “paper” the workspaces represent independent papers among which there is no connection, so they are used in a way ordinarily used in classic “paper” designing for drawing two dimensional projections and cross sections. Such projections are “flat”, i.e. they cannot be revolved in space and they have no changeable angle for observing. On every working sheet a different object can be shown or a different element of a complex object whose own drawing is also present in one or more work spaces. The assembly of work spaces in the regime “paper” represents the “paper space” of AutoCad. The views and projections of a three dimensional model cannot be activated in the paper space, and objects drawn in the space are not shown at all in the 3D modeling space.