What is AutoCAD?
AutoCAD is software for drafting and design, formally known as CAD software. CAD stands for Computer Assisted Drafting/Design. AutoCAD runs on a PC under a Windows operating systems. Autodesk introduced AutoCAD in December, 1982 and it has long been a leader in the CAD field.
AutoCAD has been very widely adopted throughout the world for its highly developed two dimensional drafting capabilities. It also has three dimensional graphics and modeling capabilities.
AutoCAD is a principal component of Mechanical Desktop (solid modeling software) and works very nicely with 3D Studio (rendering and animation software), both of which are produced by Autodesk. AutoCAD drawing files can be easily imported into many other software packages.
AutoCAD is a very capable software package right from the box. But it is programmed as general purpose drafting and design software. Since it is not geared to any particular specialty, many users find that they must either purchase third party software to run with AutoCAD and thus enhance its native capabilities, or they must customize AutoCAD themselves in order to be most productive. Even among those who work in the same field and use AutoCAD to achieve the same end, everyone uses AutoCAD differently just because of differences in individual capabilities and personal patterns of work.
So AutoCAD begs for customization. One of AutoCAD's greatest strengths is the fact that it can be tailored to suit a wide variety of disciplines and different users. You are most efficient when you customize AutoCAD to suit your particular field of work and your particular work patterns.
What is AutoLISP?
AutoLISP is the programming language which operates within AutoCAD to enhance and customize its native abilities. It is supplied without additional cost as a standard component of AutoCAD. (If you have AutoCAD, you have AutoLISP.)
AutoLISP can be used to customize AutoCAD in two principal ways. First, AutoLISP can automate repetitive procedures. This saves the user time and can eliminate many errors. Second, AutoLISP can enhance AutoCAD, giving it new commands and features, all the way from doing calculations to creating complete drawings and more.
AutoLISP was developed from the LISP programming language, which has been around for a long time. AutoLISP, while it retains the syntax of LISP, is streamlined to run inside AutoCAD and has many added functions so it can interact with both the AutoCAD commands and the drawing database.
AutoLISP has always been an interpreted language rather than a compiled language, although a programming environment including a compiler is now available. A program can be written with any text editor, saved in a plain ASCII text file, then loaded into memory inside AutoCAD. Once loaded, the program can be run from the Command prompt or from a pull-down menu, just like any other AutoCAD command.
Not only does AutoCAD come with the AutoLISP language already built in, but also with numerous sample AutoLISP programs found in a "sample" directory. Also many more programs are available at a price from third party vendors. And there are also many programs that are available free over the internet. All of these written programs can enhance your productivity with AutoCAD, but you will find that the programs that are most helpful to you are the ones that you write yourself, or the ones you have written to meet your specific needs.