What computer software is used to create CAD drawings?

anonymous asked: Specifically, two-dimensional CAD drawings that can be drawn to scale. Below is an example of one (click on the download link to view the plans):
http://www.littlemachineshop.com/Projects/OscillatingEngine.php
I already know that this is a PDF file, but what is the name of the software used to create these plans? Also, what are some more software programs [...]

is there any softwares which are related to, or are similar to Computer Aided Design, which you can buy ?

D asked: i need computer aided design software for my architecture course.. but cannot get my hands on a copy of this software.. but is there any other software which is similar, that i can buy in the shops, which are just as good as CAD

What kind of computer software classes should I take to start learning about Interior Design?

Jessica L asked: I want to start taking some cad classes to get me familiar. Any suggestions? Thanks!