Lies

I feel like lying is all around us, like it has become such a typical part of the day that no one ever pays attention to it anymore. I don't understand why people lie. Every time I catch people in a lie it confuses me more and more, because sometimes the lie is about the dumbest things. Why is it that society has fallen into such comfort in lying that no one feels the need to be honest anymore? I, personally, am a horrible liar, and I know it is incredibly easy to catch me in a lie. But what about the people that have experience in this field and can keep a straight face? How do you catch them? How do you know they are lying? These hints should help..