AutoCAD is software mostly used by architects, designers, engineers and people in construction industry.
I learned to use AutoCAD when I had my on the job training in college, year 1999, and the version I used that time was R14. That time, I really need to learn the program as fast as I could because on that office, no one was doing manual drafting. Computer Aided Drafting and design class was not yet offered to year level were I was when I initiated to undergo OJT. Using it, like creating lines or shape, requires inputting commands. I was able to help in minor editing of plans and as I work on, I learned new commands and familiarizing with it becomes easy for me. I also discovered the tool bars where I just have to click it instead of typing command.
In ten years time of experience with this software, Autodesk continuously develop the program to help better the users. When I had CADD subject at school, it was then AutoCAD 2000. I find this version easier to use especially in layouting drawing to sheet. Draw objects in 1:1, meaning input actual measurements, then you just have to set it to required scale on sheet. In starting drawing you have to set the unit required, either Metric or English.
Year 2004 I was introduced with AutoCAD 2005 and learned about external referencing which was very helpful for us in documenting complex and high rise projects because we can share and work together on the same project. One can work on the level 1 while a different person can work on level 2 and another one doing the units within the levels. Features were further enhanced by AutoCAD 2007. Three dimensional modeling is also a feature of 2007 but my forte is in documentation or two dimensional drawings (the printed documents used as guide by contractors). We are still using AutoCAD 2007 although we already have the 2009 version.
I learned more in the help option. Autodesk website provides tips and tutorials too. Drawing coordination is not yet well incorporated in the features. Checking and drawing coordination is done manually.
To sum-up, without further dwelling into technical features, the program is very useful to bring the concepts into printed documents to be used. However, the cost of the initial license and upgrades of this software is really high.