Social Engineering is the art of manipulating persons so they give up confidential information. The different types of information these “artists” are trying to get can vary, but when citizens are targeted the “artists” are often trying to trick you into passing them your passkey or bank information, or access your laptop to secretly install trojan software–that let them access to your passkey and credit card information as well as giving the SE'er control over your desktop.
People use SEing tactics because it is usually simple to fool your natural inclination to believe someone than it is to discover ways to hack your software. For example, it is much simple to trick someone into giving you their password than it is for you to try hacking their password.
Protection is all about knowing what to trust. Knowing when, and when not to, to believe a person; when to trust that the person you are communicating with is really the person you think you are communicating with; when to trust that a website is or isn’t authentic; when to believe that the person on the phone is or isn’t authentic; when providing your information is or isn’t a smart idea, intelligent idea.
Ask any security manager and they will all tell you you that the weakest link in the security chain is the human who accepts a person or scenario with no proof.