A serial number is a unique code assigned to a software product, in this case, AutoCAD 2009. It is used to identify and validate the software, ensuring that it is genuine and not pirated. An activation code, on the other hand, is a code generated during the installation process, which is used to activate the software and unlock its full features.

Look for a sticker on the original CD sleeve or the back of the box.

For businesses, using unauthorized serial numbers can result in heavy fines during a software audit.